From 18b2093f4598d8ee67a8153badc93f0fa7686b8a Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Wed, 11 Dec 2024 11:01:51 -1000 Subject: sched_ext: Fix invalid irq restore in scx_ops_bypass() While adding outer irqsave/restore locking, 0e7ffff1b811 ("scx: Fix raciness in scx_ops_bypass()") forgot to convert an inner rq_unlock_irqrestore() to rq_unlock() which could re-enable IRQ prematurely leading to the following warning: raw_local_irq_restore() called with IRQs enabled WARNING: CPU: 1 PID: 96 at kernel/locking/irqflag-debug.c:10 warn_bogus_irq_restore+0x30/0x40 ... Sched_ext: create_dsq (enabling) pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : warn_bogus_irq_restore+0x30/0x40 lr : warn_bogus_irq_restore+0x30/0x40 ... Call trace: warn_bogus_irq_restore+0x30/0x40 (P) warn_bogus_irq_restore+0x30/0x40 (L) scx_ops_bypass+0x224/0x3b8 scx_ops_enable.isra.0+0x2c8/0xaa8 bpf_scx_reg+0x18/0x30 ... irq event stamp: 33739 hardirqs last enabled at (33739): [] scx_ops_bypass+0x174/0x3b8 hardirqs last disabled at (33738): [] _raw_spin_lock_irqsave+0xb4/0xd8 Drop the stray _irqrestore(). Signed-off-by: Tejun Heo Reported-by: Ihor Solodrai Link: http://lkml.kernel.org/r/qC39k3UsonrBYD_SmuxHnZIQLsuuccoCrkiqb_BT7DvH945A1_LZwE4g-5Pu9FcCtqZt4lY1HhIPi0homRuNWxkgo1rgP3bkxa0donw8kV4=@pm.me Fixes: 0e7ffff1b811 ("scx: Fix raciness in scx_ops_bypass()") Cc: stable@vger.kernel.org # v6.12 --- kernel/sched/ext.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c index 7fff1d045477..98519e6d0dcd 100644 --- a/kernel/sched/ext.c +++ b/kernel/sched/ext.c @@ -4763,7 +4763,7 @@ static void scx_ops_bypass(bool bypass) * sees scx_rq_bypassing() before moving tasks to SCX. */ if (!scx_enabled()) { - rq_unlock_irqrestore(rq, &rf); + rq_unlock(rq, &rf); continue; } -- cgit v1.2.3 From 0ef8047b737d7480a5d4c46d956e97c190f13050 Mon Sep 17 00:00:00 2001 From: Juergen Gross Date: Fri, 29 Nov 2024 16:15:54 +0100 Subject: x86/static-call: provide a way to do very early static-call updates Add static_call_update_early() for updating static-call targets in very early boot. This will be needed for support of Xen guest type specific hypercall functions. This is part of XSA-466 / CVE-2024-53241. Reported-by: Andrew Cooper Signed-off-by: Juergen Gross Co-developed-by: Peter Zijlstra Co-developed-by: Josh Poimboeuf --- kernel/static_call_inline.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/static_call_inline.c b/kernel/static_call_inline.c index 5259cda486d0..bb7d066a7c39 100644 --- a/kernel/static_call_inline.c +++ b/kernel/static_call_inline.c @@ -15,7 +15,7 @@ extern struct static_call_site __start_static_call_sites[], extern struct static_call_tramp_key __start_static_call_tramp_key[], __stop_static_call_tramp_key[]; -static int static_call_initialized; +int static_call_initialized; /* * Must be called before early_initcall() to be effective. -- cgit v1.2.3 From cc252bb592638e0f7aea40d580186c36d89526b8 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 11 Dec 2024 13:53:35 -0500 Subject: fgraph: Still initialize idle shadow stacks when starting A bug was discovered where the idle shadow stacks were not initialized for offline CPUs when starting function graph tracer, and when they came online they were not traced due to the missing shadow stack. To fix this, the idle task shadow stack initialization was moved to using the CPU hotplug callbacks. But it removed the initialization when the function graph was enabled. The problem here is that the hotplug callbacks are called when the CPUs come online, but the idle shadow stack initialization only happens if function graph is currently active. This caused the online CPUs to not get their shadow stack initialized. The idle shadow stack initialization still needs to be done when the function graph is registered, as they will not be allocated if function graph is not registered. Cc: stable@vger.kernel.org Cc: Masami Hiramatsu Cc: Mathieu Desnoyers Link: https://lore.kernel.org/20241211135335.094ba282@batman.local.home Fixes: 2c02f7375e65 ("fgraph: Use CPU hotplug mechanism to initialize idle shadow stacks") Reported-by: Linus Walleij Tested-by: Linus Walleij Closes: https://lore.kernel.org/all/CACRpkdaTBrHwRbbrphVy-=SeDz6MSsXhTKypOtLrTQ+DgGAOcQ@mail.gmail.com/ Signed-off-by: Steven Rostedt (Google) --- kernel/trace/fgraph.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c index 0bf78517b5d4..ddedcb50917f 100644 --- a/kernel/trace/fgraph.c +++ b/kernel/trace/fgraph.c @@ -1215,7 +1215,7 @@ void fgraph_update_pid_func(void) static int start_graph_tracing(void) { unsigned long **ret_stack_list; - int ret; + int ret, cpu; ret_stack_list = kcalloc(FTRACE_RETSTACK_ALLOC_SIZE, sizeof(*ret_stack_list), GFP_KERNEL); @@ -1223,6 +1223,12 @@ static int start_graph_tracing(void) if (!ret_stack_list) return -ENOMEM; + /* The cpu_boot init_task->ret_stack will never be freed */ + for_each_online_cpu(cpu) { + if (!idle_task(cpu)->ret_stack) + ftrace_graph_init_idle_task(idle_task(cpu), cpu); + } + do { ret = alloc_retstack_tasklist(ret_stack_list); } while (ret == -EAGAIN); -- cgit v1.2.3 From 166438a432d76c68d3f0da60667248f3c2303d6c Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Mon, 16 Dec 2024 16:46:33 -0500 Subject: ftrace: Do not find "true_parent" if HAVE_DYNAMIC_FTRACE_WITH_ARGS is not set When function tracing and function graph tracing are both enabled (in different instances) the "parent" of some of the function tracing events is "return_to_handler" which is the trampoline used by function graph tracing. To fix this, ftrace_get_true_parent_ip() was introduced that returns the "true" parent ip instead of the trampoline. To do this, the ftrace_regs_get_stack_pointer() is used, which uses kernel_stack_pointer(). The problem is that microblaze does not implement kerenl_stack_pointer() so when function graph tracing is enabled, the build fails. But microblaze also does not enabled HAVE_DYNAMIC_FTRACE_WITH_ARGS. That option has to be enabled by the architecture to reliably get the values from the fregs parameter passed in. When that config is not set, the architecture can also pass in NULL, which is not tested for in that function and could cause the kernel to crash. Cc: Masami Hiramatsu Cc: Mathieu Desnoyers Cc: Mark Rutland Cc: Al Viro Cc: Michal Simek Cc: Jeff Xie Link: https://lore.kernel.org/20241216164633.6df18e87@gandalf.local.home Fixes: 60b1f578b578 ("ftrace: Get the true parent ip for function tracer") Reported-by: Al Viro Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace_functions.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/trace/trace_functions.c b/kernel/trace/trace_functions.c index 74c353164ca1..d358c9935164 100644 --- a/kernel/trace/trace_functions.c +++ b/kernel/trace/trace_functions.c @@ -176,7 +176,8 @@ static void function_trace_start(struct trace_array *tr) tracing_reset_online_cpus(&tr->array_buffer); } -#ifdef CONFIG_FUNCTION_GRAPH_TRACER +/* fregs are guaranteed not to be NULL if HAVE_DYNAMIC_FTRACE_WITH_ARGS is set */ +#if defined(CONFIG_FUNCTION_GRAPH_TRACER) && defined(CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS) static __always_inline unsigned long function_get_true_parent_ip(unsigned long parent_ip, struct ftrace_regs *fregs) { -- cgit v1.2.3 From a6629626c584200daf495cc9a740048b455addcd Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Mon, 16 Dec 2024 21:41:19 -0500 Subject: tracing: Fix test_event_printk() to process entire print argument The test_event_printk() analyzes print formats of trace events looking for cases where it may dereference a pointer that is not in the ring buffer which can possibly be a bug when the trace event is read from the ring buffer and the content of that pointer no longer exists. The function needs to accurately go from one print format argument to the next. It handles quotes and parenthesis that may be included in an argument. When it finds the start of the next argument, it uses a simple "c = strstr(fmt + i, ',')" to find the end of that argument! In order to include "%s" dereferencing, it needs to process the entire content of the print format argument and not just the content of the first ',' it finds. As there may be content like: ({ const char *saved_ptr = trace_seq_buffer_ptr(p); static const char *access_str[] = { "---", "--x", "w--", "w-x", "-u-", "-ux", "wu-", "wux" }; union kvm_mmu_page_role role; role.word = REC->role; trace_seq_printf(p, "sp gen %u gfn %llx l%u %u-byte q%u%s %s%s" " %snxe %sad root %u %s%c", REC->mmu_valid_gen, REC->gfn, role.level, role.has_4_byte_gpte ? 4 : 8, role.quadrant, role.direct ? " direct" : "", access_str[role.access], role.invalid ? " invalid" : "", role.efer_nx ? "" : "!", role.ad_disabled ? "!" : "", REC->root_count, REC->unsync ? "unsync" : "sync", 0); saved_ptr; }) Which is an example of a full argument of an existing event. As the code already handles finding the next print format argument, process the argument at the end of it and not the start of it. This way it has both the start of the argument as well as the end of it. Add a helper function "process_pointer()" that will do the processing during the loop as well as at the end. It also makes the code cleaner and easier to read. Cc: stable@vger.kernel.org Cc: Masami Hiramatsu Cc: Mark Rutland Cc: Mathieu Desnoyers Cc: Andrew Morton Cc: Al Viro Cc: Linus Torvalds Link: https://lore.kernel.org/20241217024720.362271189@goodmis.org Fixes: 5013f454a352c ("tracing: Add check of trace event print fmts for dereferencing pointers") Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace_events.c | 82 +++++++++++++++++++++++++++++---------------- 1 file changed, 53 insertions(+), 29 deletions(-) (limited to 'kernel') diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index 77e68efbd43e..14e160a5b905 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -265,8 +265,7 @@ static bool test_field(const char *fmt, struct trace_event_call *call) len = p - fmt; for (; field->type; field++) { - if (strncmp(field->name, fmt, len) || - field->name[len]) + if (strncmp(field->name, fmt, len) || field->name[len]) continue; array_descriptor = strchr(field->type, '['); /* This is an array and is OK to dereference. */ @@ -275,6 +274,32 @@ static bool test_field(const char *fmt, struct trace_event_call *call) return false; } +/* Return true if the argument pointer is safe */ +static bool process_pointer(const char *fmt, int len, struct trace_event_call *call) +{ + const char *r, *e, *a; + + e = fmt + len; + + /* Find the REC-> in the argument */ + r = strstr(fmt, "REC->"); + if (r && r < e) { + /* + * Addresses of events on the buffer, or an array on the buffer is + * OK to dereference. There's ways to fool this, but + * this is to catch common mistakes, not malicious code. + */ + a = strchr(fmt, '&'); + if ((a && (a < r)) || test_field(r, call)) + return true; + } else if ((r = strstr(fmt, "__get_dynamic_array(")) && r < e) { + return true; + } else if ((r = strstr(fmt, "__get_sockaddr(")) && r < e) { + return true; + } + return false; +} + /* * Examine the print fmt of the event looking for unsafe dereference * pointers using %p* that could be recorded in the trace event and @@ -285,12 +310,12 @@ static void test_event_printk(struct trace_event_call *call) { u64 dereference_flags = 0; bool first = true; - const char *fmt, *c, *r, *a; + const char *fmt; int parens = 0; char in_quote = 0; int start_arg = 0; int arg = 0; - int i; + int i, e; fmt = call->print_fmt; @@ -403,42 +428,41 @@ static void test_event_printk(struct trace_event_call *call) case ',': if (in_quote || parens) continue; + e = i; i++; while (isspace(fmt[i])) i++; - start_arg = i; - if (!(dereference_flags & (1ULL << arg))) - goto next_arg; - /* Find the REC-> in the argument */ - c = strchr(fmt + i, ','); - r = strstr(fmt + i, "REC->"); - if (r && (!c || r < c)) { - /* - * Addresses of events on the buffer, - * or an array on the buffer is - * OK to dereference. - * There's ways to fool this, but - * this is to catch common mistakes, - * not malicious code. - */ - a = strchr(fmt + i, '&'); - if ((a && (a < r)) || test_field(r, call)) + /* + * If start_arg is zero, then this is the start of the + * first argument. The processing of the argument happens + * when the end of the argument is found, as it needs to + * handle paranthesis and such. + */ + if (!start_arg) { + start_arg = i; + /* Balance out the i++ in the for loop */ + i--; + continue; + } + + if (dereference_flags & (1ULL << arg)) { + if (process_pointer(fmt + start_arg, e - start_arg, call)) dereference_flags &= ~(1ULL << arg); - } else if ((r = strstr(fmt + i, "__get_dynamic_array(")) && - (!c || r < c)) { - dereference_flags &= ~(1ULL << arg); - } else if ((r = strstr(fmt + i, "__get_sockaddr(")) && - (!c || r < c)) { - dereference_flags &= ~(1ULL << arg); } - next_arg: - i--; + start_arg = i; arg++; + /* Balance out the i++ in the for loop */ + i--; } } + if (dereference_flags & (1ULL << arg)) { + if (process_pointer(fmt + start_arg, i - start_arg, call)) + dereference_flags &= ~(1ULL << arg); + } + /* * If you triggered the below warning, the trace event reported * uses an unsafe dereference pointer %p*. As the data stored -- cgit v1.2.3 From 917110481f6bc1c96b1e54b62bb114137fbc6d17 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Mon, 16 Dec 2024 21:41:20 -0500 Subject: tracing: Add missing helper functions in event pointer dereference check The process_pointer() helper function looks to see if various trace event macros are used. These macros are for storing data in the event. This makes it safe to dereference as the dereference will then point into the event on the ring buffer where the content of the data stays with the event itself. A few helper functions were missing. Those were: __get_rel_dynamic_array() __get_dynamic_array_len() __get_rel_dynamic_array_len() __get_rel_sockaddr() Also add a helper function find_print_string() to not need to use a middle man variable to test if the string exists. Cc: stable@vger.kernel.org Cc: Masami Hiramatsu Cc: Mark Rutland Cc: Mathieu Desnoyers Cc: Andrew Morton Cc: Al Viro Cc: Linus Torvalds Link: https://lore.kernel.org/20241217024720.521836792@goodmis.org Fixes: 5013f454a352c ("tracing: Add check of trace event print fmts for dereferencing pointers") Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace_events.c | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-) (limited to 'kernel') diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index 14e160a5b905..df75c06bb23f 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -274,6 +274,15 @@ static bool test_field(const char *fmt, struct trace_event_call *call) return false; } +/* Look for a string within an argument */ +static bool find_print_string(const char *arg, const char *str, const char *end) +{ + const char *r; + + r = strstr(arg, str); + return r && r < end; +} + /* Return true if the argument pointer is safe */ static bool process_pointer(const char *fmt, int len, struct trace_event_call *call) { @@ -292,9 +301,17 @@ static bool process_pointer(const char *fmt, int len, struct trace_event_call *c a = strchr(fmt, '&'); if ((a && (a < r)) || test_field(r, call)) return true; - } else if ((r = strstr(fmt, "__get_dynamic_array(")) && r < e) { + } else if (find_print_string(fmt, "__get_dynamic_array(", e)) { + return true; + } else if (find_print_string(fmt, "__get_rel_dynamic_array(", e)) { + return true; + } else if (find_print_string(fmt, "__get_dynamic_array_len(", e)) { + return true; + } else if (find_print_string(fmt, "__get_rel_dynamic_array_len(", e)) { + return true; + } else if (find_print_string(fmt, "__get_sockaddr(", e)) { return true; - } else if ((r = strstr(fmt, "__get_sockaddr(")) && r < e) { + } else if (find_print_string(fmt, "__get_rel_sockaddr(", e)) { return true; } return false; -- cgit v1.2.3 From 65a25d9f7ac02e0cf361356e834d1c71d36acca9 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Mon, 16 Dec 2024 21:41:21 -0500 Subject: tracing: Add "%s" check in test_event_printk() The test_event_printk() code makes sure that when a trace event is registered, any dereferenced pointers in from the event's TP_printk() are pointing to content in the ring buffer. But currently it does not handle "%s", as there's cases where the string pointer saved in the ring buffer points to a static string in the kernel that will never be freed. As that is a valid case, the pointer needs to be checked at runtime. Currently the runtime check is done via trace_check_vprintf(), but to not have to replicate everything in vsnprintf() it does some logic with the va_list that may not be reliable across architectures. In order to get rid of that logic, more work in the test_event_printk() needs to be done. Some of the strings can be validated at this time when it is obvious the string is valid because the string will be saved in the ring buffer content. Do all the validation of strings in the ring buffer at boot in test_event_printk(), and make sure that the field of the strings that point into the kernel are accessible. This will allow adding checks at runtime that will validate the fields themselves and not rely on paring the TP_printk() format at runtime. Cc: stable@vger.kernel.org Cc: Masami Hiramatsu Cc: Mark Rutland Cc: Mathieu Desnoyers Cc: Andrew Morton Cc: Al Viro Cc: Linus Torvalds Link: https://lore.kernel.org/20241217024720.685917008@goodmis.org Fixes: 5013f454a352c ("tracing: Add check of trace event print fmts for dereferencing pointers") Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace_events.c | 104 +++++++++++++++++++++++++++++++++++++------- 1 file changed, 89 insertions(+), 15 deletions(-) (limited to 'kernel') diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index df75c06bb23f..521ad2fd1fe7 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -244,19 +244,16 @@ int trace_event_get_offsets(struct trace_event_call *call) return tail->offset + tail->size; } -/* - * Check if the referenced field is an array and return true, - * as arrays are OK to dereference. - */ -static bool test_field(const char *fmt, struct trace_event_call *call) + +static struct trace_event_fields *find_event_field(const char *fmt, + struct trace_event_call *call) { struct trace_event_fields *field = call->class->fields_array; - const char *array_descriptor; const char *p = fmt; int len; if (!(len = str_has_prefix(fmt, "REC->"))) - return false; + return NULL; fmt += len; for (p = fmt; *p; p++) { if (!isalnum(*p) && *p != '_') @@ -267,11 +264,26 @@ static bool test_field(const char *fmt, struct trace_event_call *call) for (; field->type; field++) { if (strncmp(field->name, fmt, len) || field->name[len]) continue; - array_descriptor = strchr(field->type, '['); - /* This is an array and is OK to dereference. */ - return array_descriptor != NULL; + + return field; } - return false; + return NULL; +} + +/* + * Check if the referenced field is an array and return true, + * as arrays are OK to dereference. + */ +static bool test_field(const char *fmt, struct trace_event_call *call) +{ + struct trace_event_fields *field; + + field = find_event_field(fmt, call); + if (!field) + return false; + + /* This is an array and is OK to dereference. */ + return strchr(field->type, '[') != NULL; } /* Look for a string within an argument */ @@ -317,6 +329,53 @@ static bool process_pointer(const char *fmt, int len, struct trace_event_call *c return false; } +/* Return true if the string is safe */ +static bool process_string(const char *fmt, int len, struct trace_event_call *call) +{ + const char *r, *e, *s; + + e = fmt + len; + + /* + * There are several helper functions that return strings. + * If the argument contains a function, then assume its field is valid. + * It is considered that the argument has a function if it has: + * alphanumeric or '_' before a parenthesis. + */ + s = fmt; + do { + r = strstr(s, "("); + if (!r || r >= e) + break; + for (int i = 1; r - i >= s; i++) { + char ch = *(r - i); + if (isspace(ch)) + continue; + if (isalnum(ch) || ch == '_') + return true; + /* Anything else, this isn't a function */ + break; + } + /* A function could be wrapped in parethesis, try the next one */ + s = r + 1; + } while (s < e); + + /* + * If there's any strings in the argument consider this arg OK as it + * could be: REC->field ? "foo" : "bar" and we don't want to get into + * verifying that logic here. + */ + if (find_print_string(fmt, "\"", e)) + return true; + + /* Dereferenced strings are also valid like any other pointer */ + if (process_pointer(fmt, len, call)) + return true; + + /* Make sure the field is found, and consider it OK for now if it is */ + return find_event_field(fmt, call) != NULL; +} + /* * Examine the print fmt of the event looking for unsafe dereference * pointers using %p* that could be recorded in the trace event and @@ -326,6 +385,7 @@ static bool process_pointer(const char *fmt, int len, struct trace_event_call *c static void test_event_printk(struct trace_event_call *call) { u64 dereference_flags = 0; + u64 string_flags = 0; bool first = true; const char *fmt; int parens = 0; @@ -416,8 +476,16 @@ static void test_event_printk(struct trace_event_call *call) star = true; continue; } - if ((fmt[i + j] == 's') && star) - arg++; + if ((fmt[i + j] == 's')) { + if (star) + arg++; + if (WARN_ONCE(arg == 63, + "Too many args for event: %s", + trace_event_name(call))) + return; + dereference_flags |= 1ULL << arg; + string_flags |= 1ULL << arg; + } break; } break; @@ -464,7 +532,10 @@ static void test_event_printk(struct trace_event_call *call) } if (dereference_flags & (1ULL << arg)) { - if (process_pointer(fmt + start_arg, e - start_arg, call)) + if (string_flags & (1ULL << arg)) { + if (process_string(fmt + start_arg, e - start_arg, call)) + dereference_flags &= ~(1ULL << arg); + } else if (process_pointer(fmt + start_arg, e - start_arg, call)) dereference_flags &= ~(1ULL << arg); } @@ -476,7 +547,10 @@ static void test_event_printk(struct trace_event_call *call) } if (dereference_flags & (1ULL << arg)) { - if (process_pointer(fmt + start_arg, i - start_arg, call)) + if (string_flags & (1ULL << arg)) { + if (process_string(fmt + start_arg, i - start_arg, call)) + dereference_flags &= ~(1ULL << arg); + } else if (process_pointer(fmt + start_arg, i - start_arg, call)) dereference_flags &= ~(1ULL << arg); } -- cgit v1.2.3 From afd2627f727b89496d79a6b934a025fc916d4ded Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Mon, 16 Dec 2024 21:41:22 -0500 Subject: tracing: Check "%s" dereference via the field and not the TP_printk format The TP_printk() portion of a trace event is executed at the time a event is read from the trace. This can happen seconds, minutes, hours, days, months, years possibly later since the event was recorded. If the print format contains a dereference to a string via "%s", and that string was allocated, there's a chance that string could be freed before it is read by the trace file. To protect against such bugs, there are two functions that verify the event. The first one is test_event_printk(), which is called when the event is created. It reads the TP_printk() format as well as its arguments to make sure nothing may be dereferencing a pointer that was not copied into the ring buffer along with the event. If it is, it will trigger a WARN_ON(). For strings that use "%s", it is not so easy. The string may not reside in the ring buffer but may still be valid. Strings that are static and part of the kernel proper which will not be freed for the life of the running system, are safe to dereference. But to know if it is a pointer to a static string or to something on the heap can not be determined until the event is triggered. This brings us to the second function that tests for the bad dereferencing of strings, trace_check_vprintf(). It would walk through the printf format looking for "%s", and when it finds it, it would validate that the pointer is safe to read. If not, it would produces a WARN_ON() as well and write into the ring buffer "[UNSAFE-MEMORY]". The problem with this is how it used va_list to have vsnprintf() handle all the cases that it didn't need to check. Instead of re-implementing vsnprintf(), it would make a copy of the format up to the %s part, and call vsnprintf() with the current va_list ap variable, where the ap would then be ready to point at the string in question. For architectures that passed va_list by reference this was possible. For architectures that passed it by copy it was not. A test_can_verify() function was used to differentiate between the two, and if it wasn't possible, it would disable it. Even for architectures where this was feasible, it was a stretch to rely on such a method that is undocumented, and could cause issues later on with new optimizations of the compiler. Instead, the first function test_event_printk() was updated to look at "%s" as well. If the "%s" argument is a pointer outside the event in the ring buffer, it would find the field type of the event that is the problem and mark the structure with a new flag called "needs_test". The event itself will be marked by TRACE_EVENT_FL_TEST_STR to let it be known that this event has a field that needs to be verified before the event can be printed using the printf format. When the event fields are created from the field type structure, the fields would copy the field type's "needs_test" value. Finally, before being printed, a new function ignore_event() is called which will check if the event has the TEST_STR flag set (if not, it returns false). If the flag is set, it then iterates through the events fields looking for the ones that have the "needs_test" flag set. Then it uses the offset field from the field structure to find the pointer in the ring buffer event. It runs the tests to make sure that pointer is safe to print and if not, it triggers the WARN_ON() and also adds to the trace output that the event in question has an unsafe memory access. The ignore_event() makes the trace_check_vprintf() obsolete so it is removed. Link: https://lore.kernel.org/all/CAHk-=wh3uOnqnZPpR0PeLZZtyWbZLboZ7cHLCKRWsocvs9Y7hQ@mail.gmail.com/ Cc: stable@vger.kernel.org Cc: Masami Hiramatsu Cc: Mark Rutland Cc: Mathieu Desnoyers Cc: Andrew Morton Cc: Al Viro Cc: Linus Torvalds Link: https://lore.kernel.org/20241217024720.848621576@goodmis.org Fixes: 5013f454a352c ("tracing: Add check of trace event print fmts for dereferencing pointers") Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace.c | 255 +++++++++----------------------------------- kernel/trace/trace.h | 6 +- kernel/trace/trace_events.c | 32 ++++-- kernel/trace/trace_output.c | 6 +- 4 files changed, 83 insertions(+), 216 deletions(-) (limited to 'kernel') diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index be62f0ea1814..7cc18b9bce27 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -3611,17 +3611,12 @@ char *trace_iter_expand_format(struct trace_iterator *iter) } /* Returns true if the string is safe to dereference from an event */ -static bool trace_safe_str(struct trace_iterator *iter, const char *str, - bool star, int len) +static bool trace_safe_str(struct trace_iterator *iter, const char *str) { unsigned long addr = (unsigned long)str; struct trace_event *trace_event; struct trace_event_call *event; - /* Ignore strings with no length */ - if (star && !len) - return true; - /* OK if part of the event data */ if ((addr >= (unsigned long)iter->ent) && (addr < (unsigned long)iter->ent + iter->ent_size)) @@ -3661,181 +3656,69 @@ static bool trace_safe_str(struct trace_iterator *iter, const char *str, return false; } -static DEFINE_STATIC_KEY_FALSE(trace_no_verify); - -static int test_can_verify_check(const char *fmt, ...) -{ - char buf[16]; - va_list ap; - int ret; - - /* - * The verifier is dependent on vsnprintf() modifies the va_list - * passed to it, where it is sent as a reference. Some architectures - * (like x86_32) passes it by value, which means that vsnprintf() - * does not modify the va_list passed to it, and the verifier - * would then need to be able to understand all the values that - * vsnprintf can use. If it is passed by value, then the verifier - * is disabled. - */ - va_start(ap, fmt); - vsnprintf(buf, 16, "%d", ap); - ret = va_arg(ap, int); - va_end(ap); - - return ret; -} - -static void test_can_verify(void) -{ - if (!test_can_verify_check("%d %d", 0, 1)) { - pr_info("trace event string verifier disabled\n"); - static_branch_inc(&trace_no_verify); - } -} - /** - * trace_check_vprintf - Check dereferenced strings while writing to the seq buffer + * ignore_event - Check dereferenced fields while writing to the seq buffer * @iter: The iterator that holds the seq buffer and the event being printed - * @fmt: The format used to print the event - * @ap: The va_list holding the data to print from @fmt. * - * This writes the data into the @iter->seq buffer using the data from - * @fmt and @ap. If the format has a %s, then the source of the string - * is examined to make sure it is safe to print, otherwise it will - * warn and print "[UNSAFE MEMORY]" in place of the dereferenced string - * pointer. + * At boot up, test_event_printk() will flag any event that dereferences + * a string with "%s" that does exist in the ring buffer. It may still + * be valid, as the string may point to a static string in the kernel + * rodata that never gets freed. But if the string pointer is pointing + * to something that was allocated, there's a chance that it can be freed + * by the time the user reads the trace. This would cause a bad memory + * access by the kernel and possibly crash the system. + * + * This function will check if the event has any fields flagged as needing + * to be checked at runtime and perform those checks. + * + * If it is found that a field is unsafe, it will write into the @iter->seq + * a message stating what was found to be unsafe. + * + * @return: true if the event is unsafe and should be ignored, + * false otherwise. */ -void trace_check_vprintf(struct trace_iterator *iter, const char *fmt, - va_list ap) +bool ignore_event(struct trace_iterator *iter) { - long text_delta = 0; - long data_delta = 0; - const char *p = fmt; - const char *str; - bool good; - int i, j; + struct ftrace_event_field *field; + struct trace_event *trace_event; + struct trace_event_call *event; + struct list_head *head; + struct trace_seq *seq; + const void *ptr; - if (WARN_ON_ONCE(!fmt)) - return; + trace_event = ftrace_find_event(iter->ent->type); - if (static_branch_unlikely(&trace_no_verify)) - goto print; + seq = &iter->seq; - /* - * When the kernel is booted with the tp_printk command line - * parameter, trace events go directly through to printk(). - * It also is checked by this function, but it does not - * have an associated trace_array (tr) for it. - */ - if (iter->tr) { - text_delta = iter->tr->text_delta; - data_delta = iter->tr->data_delta; + if (!trace_event) { + trace_seq_printf(seq, "EVENT ID %d NOT FOUND?\n", iter->ent->type); + return true; } - /* Don't bother checking when doing a ftrace_dump() */ - if (iter->fmt == static_fmt_buf) - goto print; - - while (*p) { - bool star = false; - int len = 0; - - j = 0; - - /* - * We only care about %s and variants - * as well as %p[sS] if delta is non-zero - */ - for (i = 0; p[i]; i++) { - if (i + 1 >= iter->fmt_size) { - /* - * If we can't expand the copy buffer, - * just print it. - */ - if (!trace_iter_expand_format(iter)) - goto print; - } - - if (p[i] == '\\' && p[i+1]) { - i++; - continue; - } - if (p[i] == '%') { - /* Need to test cases like %08.*s */ - for (j = 1; p[i+j]; j++) { - if (isdigit(p[i+j]) || - p[i+j] == '.') - continue; - if (p[i+j] == '*') { - star = true; - continue; - } - break; - } - if (p[i+j] == 's') - break; - - if (text_delta && p[i+1] == 'p' && - ((p[i+2] == 's' || p[i+2] == 'S'))) - break; - - star = false; - } - j = 0; - } - /* If no %s found then just print normally */ - if (!p[i]) - break; - - /* Copy up to the %s, and print that */ - strncpy(iter->fmt, p, i); - iter->fmt[i] = '\0'; - trace_seq_vprintf(&iter->seq, iter->fmt, ap); + event = container_of(trace_event, struct trace_event_call, event); + if (!(event->flags & TRACE_EVENT_FL_TEST_STR)) + return false; - /* Add delta to %pS pointers */ - if (p[i+1] == 'p') { - unsigned long addr; - char fmt[4]; + head = trace_get_fields(event); + if (!head) { + trace_seq_printf(seq, "FIELDS FOR EVENT '%s' NOT FOUND?\n", + trace_event_name(event)); + return true; + } - fmt[0] = '%'; - fmt[1] = 'p'; - fmt[2] = p[i+2]; /* Either %ps or %pS */ - fmt[3] = '\0'; + /* Offsets are from the iter->ent that points to the raw event */ + ptr = iter->ent; - addr = va_arg(ap, unsigned long); - addr += text_delta; - trace_seq_printf(&iter->seq, fmt, (void *)addr); + list_for_each_entry(field, head, link) { + const char *str; + bool good; - p += i + 3; + if (!field->needs_test) continue; - } - /* - * If iter->seq is full, the above call no longer guarantees - * that ap is in sync with fmt processing, and further calls - * to va_arg() can return wrong positional arguments. - * - * Ensure that ap is no longer used in this case. - */ - if (iter->seq.full) { - p = ""; - break; - } - - if (star) - len = va_arg(ap, int); - - /* The ap now points to the string data of the %s */ - str = va_arg(ap, const char *); + str = *(const char **)(ptr + field->offset); - good = trace_safe_str(iter, str, star, len); - - /* Could be from the last boot */ - if (data_delta && !good) { - str += data_delta; - good = trace_safe_str(iter, str, star, len); - } + good = trace_safe_str(iter, str); /* * If you hit this warning, it is likely that the @@ -3846,44 +3729,14 @@ void trace_check_vprintf(struct trace_iterator *iter, const char *fmt, * instead. See samples/trace_events/trace-events-sample.h * for reference. */ - if (WARN_ONCE(!good, "fmt: '%s' current_buffer: '%s'", - fmt, seq_buf_str(&iter->seq.seq))) { - int ret; - - /* Try to safely read the string */ - if (star) { - if (len + 1 > iter->fmt_size) - len = iter->fmt_size - 1; - if (len < 0) - len = 0; - ret = copy_from_kernel_nofault(iter->fmt, str, len); - iter->fmt[len] = 0; - star = false; - } else { - ret = strncpy_from_kernel_nofault(iter->fmt, str, - iter->fmt_size); - } - if (ret < 0) - trace_seq_printf(&iter->seq, "(0x%px)", str); - else - trace_seq_printf(&iter->seq, "(0x%px:%s)", - str, iter->fmt); - str = "[UNSAFE-MEMORY]"; - strcpy(iter->fmt, "%s"); - } else { - strncpy(iter->fmt, p + i, j + 1); - iter->fmt[j+1] = '\0'; + if (WARN_ONCE(!good, "event '%s' has unsafe pointer field '%s'", + trace_event_name(event), field->name)) { + trace_seq_printf(seq, "EVENT %s: HAS UNSAFE POINTER FIELD '%s'\n", + trace_event_name(event), field->name); + return true; } - if (star) - trace_seq_printf(&iter->seq, iter->fmt, len, str); - else - trace_seq_printf(&iter->seq, iter->fmt, str); - - p += i + j + 1; } - print: - if (*p) - trace_seq_vprintf(&iter->seq, p, ap); + return false; } const char *trace_event_format(struct trace_iterator *iter, const char *fmt) @@ -10777,8 +10630,6 @@ __init static int tracer_alloc_buffers(void) register_snapshot_cmd(); - test_can_verify(); - return 0; out_free_pipe_cpumask: diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 266740b4e121..9691b47b5f3d 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -667,9 +667,8 @@ void trace_buffer_unlock_commit_nostack(struct trace_buffer *buffer, bool trace_is_tracepoint_string(const char *str); const char *trace_event_format(struct trace_iterator *iter, const char *fmt); -void trace_check_vprintf(struct trace_iterator *iter, const char *fmt, - va_list ap) __printf(2, 0); char *trace_iter_expand_format(struct trace_iterator *iter); +bool ignore_event(struct trace_iterator *iter); int trace_empty(struct trace_iterator *iter); @@ -1413,7 +1412,8 @@ struct ftrace_event_field { int filter_type; int offset; int size; - int is_signed; + unsigned int is_signed:1; + unsigned int needs_test:1; int len; }; diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index 521ad2fd1fe7..1545cc8b49d0 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -82,7 +82,7 @@ static int system_refcount_dec(struct event_subsystem *system) } static struct ftrace_event_field * -__find_event_field(struct list_head *head, char *name) +__find_event_field(struct list_head *head, const char *name) { struct ftrace_event_field *field; @@ -114,7 +114,8 @@ trace_find_event_field(struct trace_event_call *call, char *name) static int __trace_define_field(struct list_head *head, const char *type, const char *name, int offset, int size, - int is_signed, int filter_type, int len) + int is_signed, int filter_type, int len, + int need_test) { struct ftrace_event_field *field; @@ -133,6 +134,7 @@ static int __trace_define_field(struct list_head *head, const char *type, field->offset = offset; field->size = size; field->is_signed = is_signed; + field->needs_test = need_test; field->len = len; list_add(&field->link, head); @@ -151,13 +153,13 @@ int trace_define_field(struct trace_event_call *call, const char *type, head = trace_get_fields(call); return __trace_define_field(head, type, name, offset, size, - is_signed, filter_type, 0); + is_signed, filter_type, 0, 0); } EXPORT_SYMBOL_GPL(trace_define_field); static int trace_define_field_ext(struct trace_event_call *call, const char *type, const char *name, int offset, int size, int is_signed, - int filter_type, int len) + int filter_type, int len, int need_test) { struct list_head *head; @@ -166,13 +168,13 @@ static int trace_define_field_ext(struct trace_event_call *call, const char *typ head = trace_get_fields(call); return __trace_define_field(head, type, name, offset, size, - is_signed, filter_type, len); + is_signed, filter_type, len, need_test); } #define __generic_field(type, item, filter_type) \ ret = __trace_define_field(&ftrace_generic_fields, #type, \ #item, 0, 0, is_signed_type(type), \ - filter_type, 0); \ + filter_type, 0, 0); \ if (ret) \ return ret; @@ -181,7 +183,8 @@ static int trace_define_field_ext(struct trace_event_call *call, const char *typ "common_" #item, \ offsetof(typeof(ent), item), \ sizeof(ent.item), \ - is_signed_type(type), FILTER_OTHER, 0); \ + is_signed_type(type), FILTER_OTHER, \ + 0, 0); \ if (ret) \ return ret; @@ -332,6 +335,7 @@ static bool process_pointer(const char *fmt, int len, struct trace_event_call *c /* Return true if the string is safe */ static bool process_string(const char *fmt, int len, struct trace_event_call *call) { + struct trace_event_fields *field; const char *r, *e, *s; e = fmt + len; @@ -372,8 +376,16 @@ static bool process_string(const char *fmt, int len, struct trace_event_call *ca if (process_pointer(fmt, len, call)) return true; - /* Make sure the field is found, and consider it OK for now if it is */ - return find_event_field(fmt, call) != NULL; + /* Make sure the field is found */ + field = find_event_field(fmt, call); + if (!field) + return false; + + /* Test this field's string before printing the event */ + call->flags |= TRACE_EVENT_FL_TEST_STR; + field->needs_test = 1; + + return true; } /* @@ -2586,7 +2598,7 @@ event_define_fields(struct trace_event_call *call) ret = trace_define_field_ext(call, field->type, field->name, offset, field->size, field->is_signed, field->filter_type, - field->len); + field->len, field->needs_test); if (WARN_ON_ONCE(ret)) { pr_err("error code is %d\n", ret); break; diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c index da748b7cbc4d..03d56f711ad1 100644 --- a/kernel/trace/trace_output.c +++ b/kernel/trace/trace_output.c @@ -317,10 +317,14 @@ EXPORT_SYMBOL(trace_raw_output_prep); void trace_event_printf(struct trace_iterator *iter, const char *fmt, ...) { + struct trace_seq *s = &iter->seq; va_list ap; + if (ignore_event(iter)) + return; + va_start(ap, fmt); - trace_check_vprintf(iter, trace_event_format(iter, fmt), ap); + trace_seq_vprintf(s, trace_event_format(iter, fmt), ap); va_end(ap); } EXPORT_SYMBOL(trace_event_printf); -- cgit v1.2.3 From 4a077914578183ec397ad09f7156a357e00e5d72 Mon Sep 17 00:00:00 2001 From: John Stultz Date: Thu, 12 Dec 2024 14:21:33 -0800 Subject: locking/rtmutex: Make sure we wake anything on the wake_q when we release the lock->wait_lock Bert reported seeing occasional boot hangs when running with PREEPT_RT and bisected it down to commit 894d1b3db41c ("locking/mutex: Remove wakeups from under mutex::wait_lock"). It looks like I missed a few spots where we drop the wait_lock and potentially call into schedule without waking up the tasks on the wake_q structure. Since the tasks being woken are ww_mutex tasks they need to be able to run to release the mutex and unblock the task that currently is planning to wake them. Thus we can deadlock. So make sure we wake the wake_q tasks when we unlock the wait_lock. Closes: https://lore.kernel.org/lkml/20241211182502.2915-1-spasswolf@web.de Fixes: 894d1b3db41c ("locking/mutex: Remove wakeups from under mutex::wait_lock") Reported-by: Bert Karwatzki Signed-off-by: John Stultz Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20241212222138.2400498-1-jstultz@google.com --- kernel/locking/rtmutex.c | 18 ++++++++++++++++-- kernel/locking/rtmutex_api.c | 2 +- 2 files changed, 17 insertions(+), 3 deletions(-) (limited to 'kernel') diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c index e858de203eb6..697a56d3d949 100644 --- a/kernel/locking/rtmutex.c +++ b/kernel/locking/rtmutex.c @@ -1292,7 +1292,13 @@ static int __sched task_blocks_on_rt_mutex(struct rt_mutex_base *lock, */ get_task_struct(owner); + preempt_disable(); raw_spin_unlock_irq(&lock->wait_lock); + /* wake up any tasks on the wake_q before calling rt_mutex_adjust_prio_chain */ + wake_up_q(wake_q); + wake_q_init(wake_q); + preempt_enable(); + res = rt_mutex_adjust_prio_chain(owner, chwalk, lock, next_lock, waiter, task); @@ -1596,6 +1602,7 @@ static void __sched remove_waiter(struct rt_mutex_base *lock, * or TASK_UNINTERRUPTIBLE) * @timeout: the pre-initialized and started timer, or NULL for none * @waiter: the pre-initialized rt_mutex_waiter + * @wake_q: wake_q of tasks to wake when we drop the lock->wait_lock * * Must be called with lock->wait_lock held and interrupts disabled */ @@ -1603,7 +1610,8 @@ static int __sched rt_mutex_slowlock_block(struct rt_mutex_base *lock, struct ww_acquire_ctx *ww_ctx, unsigned int state, struct hrtimer_sleeper *timeout, - struct rt_mutex_waiter *waiter) + struct rt_mutex_waiter *waiter, + struct wake_q_head *wake_q) __releases(&lock->wait_lock) __acquires(&lock->wait_lock) { struct rt_mutex *rtm = container_of(lock, struct rt_mutex, rtmutex); @@ -1634,7 +1642,13 @@ static int __sched rt_mutex_slowlock_block(struct rt_mutex_base *lock, owner = rt_mutex_owner(lock); else owner = NULL; + preempt_disable(); raw_spin_unlock_irq(&lock->wait_lock); + if (wake_q) { + wake_up_q(wake_q); + wake_q_init(wake_q); + } + preempt_enable(); if (!owner || !rtmutex_spin_on_owner(lock, waiter, owner)) rt_mutex_schedule(); @@ -1708,7 +1722,7 @@ static int __sched __rt_mutex_slowlock(struct rt_mutex_base *lock, ret = task_blocks_on_rt_mutex(lock, waiter, current, ww_ctx, chwalk, wake_q); if (likely(!ret)) - ret = rt_mutex_slowlock_block(lock, ww_ctx, state, NULL, waiter); + ret = rt_mutex_slowlock_block(lock, ww_ctx, state, NULL, waiter, wake_q); if (likely(!ret)) { /* acquired the lock */ diff --git a/kernel/locking/rtmutex_api.c b/kernel/locking/rtmutex_api.c index 33ea31d6a7b3..191e4720e546 100644 --- a/kernel/locking/rtmutex_api.c +++ b/kernel/locking/rtmutex_api.c @@ -383,7 +383,7 @@ int __sched rt_mutex_wait_proxy_lock(struct rt_mutex_base *lock, raw_spin_lock_irq(&lock->wait_lock); /* sleep on the mutex */ set_current_state(TASK_INTERRUPTIBLE); - ret = rt_mutex_slowlock_block(lock, NULL, TASK_INTERRUPTIBLE, to, waiter); + ret = rt_mutex_slowlock_block(lock, NULL, TASK_INTERRUPTIBLE, to, waiter, NULL); /* * try_to_take_rt_mutex() sets the waiter bit unconditionally. We might * have to fix that up. -- cgit v1.2.3 From 23579010cf0a12476e96a5f1acdf78a9c5843657 Mon Sep 17 00:00:00 2001 From: Andrea Righi Date: Tue, 17 Dec 2024 20:58:13 +0100 Subject: bpf: Fix bpf_get_smp_processor_id() on !CONFIG_SMP On x86-64 calling bpf_get_smp_processor_id() in a kernel with CONFIG_SMP disabled can trigger the following bug, as pcpu_hot is unavailable: [ 8.471774] BUG: unable to handle page fault for address: 00000000936a290c [ 8.471849] #PF: supervisor read access in kernel mode [ 8.471881] #PF: error_code(0x0000) - not-present page Fix by inlining a return 0 in the !CONFIG_SMP case. Fixes: 1ae6921009e5 ("bpf: inline bpf_get_smp_processor_id() helper") Signed-off-by: Andrea Righi Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20241217195813.622568-1-arighi@nvidia.com --- kernel/bpf/verifier.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index f7f892a52a37..77f56674aaa9 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -21281,11 +21281,15 @@ patch_map_ops_generic: * changed in some incompatible and hard to support * way, it's fine to back out this inlining logic */ +#ifdef CONFIG_SMP insn_buf[0] = BPF_MOV32_IMM(BPF_REG_0, (u32)(unsigned long)&pcpu_hot.cpu_number); insn_buf[1] = BPF_MOV64_PERCPU_REG(BPF_REG_0, BPF_REG_0); insn_buf[2] = BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_0, 0); cnt = 3; - +#else + insn_buf[0] = BPF_ALU32_REG(BPF_XOR, BPF_REG_0, BPF_REG_0); + cnt = 1; +#endif new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); if (!new_prog) return -ENOMEM; -- cgit v1.2.3 From c58a812c8e49ad688f94f4b050ad5c5b388fc5d2 Mon Sep 17 00:00:00 2001 From: Edward Adam Davis Date: Wed, 18 Dec 2024 21:36:55 +0800 Subject: ring-buffer: Fix overflow in __rb_map_vma An overflow occurred when performing the following calculation: nr_pages = ((nr_subbufs + 1) << subbuf_order) - pgoff; Add a check before the calculation to avoid this problem. syzbot reported this as a slab-out-of-bounds in __rb_map_vma: BUG: KASAN: slab-out-of-bounds in __rb_map_vma+0x9ab/0xae0 kernel/trace/ring_buffer.c:7058 Read of size 8 at addr ffff8880767dd2b8 by task syz-executor187/5836 CPU: 0 UID: 0 PID: 5836 Comm: syz-executor187 Not tainted 6.13.0-rc2-syzkaller-00159-gf932fb9b4074 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/25/2024 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0xc3/0x620 mm/kasan/report.c:489 kasan_report+0xd9/0x110 mm/kasan/report.c:602 __rb_map_vma+0x9ab/0xae0 kernel/trace/ring_buffer.c:7058 ring_buffer_map+0x56e/0x9b0 kernel/trace/ring_buffer.c:7138 tracing_buffers_mmap+0xa6/0x120 kernel/trace/trace.c:8482 call_mmap include/linux/fs.h:2183 [inline] mmap_file mm/internal.h:124 [inline] __mmap_new_file_vma mm/vma.c:2291 [inline] __mmap_new_vma mm/vma.c:2355 [inline] __mmap_region+0x1786/0x2670 mm/vma.c:2456 mmap_region+0x127/0x320 mm/mmap.c:1348 do_mmap+0xc00/0xfc0 mm/mmap.c:496 vm_mmap_pgoff+0x1ba/0x360 mm/util.c:580 ksys_mmap_pgoff+0x32c/0x5c0 mm/mmap.c:542 __do_sys_mmap arch/x86/kernel/sys_x86_64.c:89 [inline] __se_sys_mmap arch/x86/kernel/sys_x86_64.c:82 [inline] __x64_sys_mmap+0x125/0x190 arch/x86/kernel/sys_x86_64.c:82 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f The reproducer for this bug is: ------------------------8<------------------------- #include #include #include #include #include int main(int argc, char **argv) { int page_size = getpagesize(); int fd; void *meta; system("echo 1 > /sys/kernel/tracing/buffer_size_kb"); fd = open("/sys/kernel/tracing/per_cpu/cpu0/trace_pipe_raw", O_RDONLY); meta = mmap(NULL, page_size, PROT_READ, MAP_SHARED, fd, page_size * 5); } ------------------------>8------------------------- Cc: stable@vger.kernel.org Fixes: 117c39200d9d7 ("ring-buffer: Introducing ring-buffer mapping functions") Link: https://lore.kernel.org/tencent_06924B6674ED771167C23CC336C097223609@qq.com Reported-by: syzbot+345e4443a21200874b18@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=345e4443a21200874b18 Signed-off-by: Edward Adam Davis Signed-off-by: Steven Rostedt (Google) --- kernel/trace/ring_buffer.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 7e257e855dd1..60210fb5b211 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -7019,7 +7019,11 @@ static int __rb_map_vma(struct ring_buffer_per_cpu *cpu_buffer, lockdep_assert_held(&cpu_buffer->mapping_lock); nr_subbufs = cpu_buffer->nr_pages + 1; /* + reader-subbuf */ - nr_pages = ((nr_subbufs + 1) << subbuf_order) - pgoff; /* + meta-page */ + nr_pages = ((nr_subbufs + 1) << subbuf_order); /* + meta-page */ + if (nr_pages <= pgoff) + return -EINVAL; + + nr_pages -= pgoff; nr_vma_pages = vma_pages(vma); if (!nr_vma_pages || nr_vma_pages > nr_pages) -- cgit v1.2.3 From 8cd63406d08110c8098e1efda8aef7ddab4db348 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 18 Dec 2024 14:15:07 -0500 Subject: trace/ring-buffer: Do not use TP_printk() formatting for boot mapped buffers The TP_printk() of a TRACE_EVENT() is a generic printf format that any developer can create for their event. It may include pointers to strings and such. A boot mapped buffer may contain data from a previous kernel where the strings addresses are different. One solution is to copy the event content and update the pointers by the recorded delta, but a simpler solution (for now) is to just use the print_fields() function to print these events. The print_fields() function just iterates the fields and prints them according to what type they are, and ignores the TP_printk() format from the event itself. To understand the difference, when printing via TP_printk() the output looks like this: 4582.696626: kmem_cache_alloc: call_site=getname_flags+0x47/0x1f0 ptr=00000000e70e10e0 bytes_req=4096 bytes_alloc=4096 gfp_flags=GFP_KERNEL node=-1 accounted=false 4582.696629: kmem_cache_alloc: call_site=alloc_empty_file+0x6b/0x110 ptr=0000000095808002 bytes_req=360 bytes_alloc=384 gfp_flags=GFP_KERNEL node=-1 accounted=false 4582.696630: kmem_cache_alloc: call_site=security_file_alloc+0x24/0x100 ptr=00000000576339c3 bytes_req=16 bytes_alloc=16 gfp_flags=GFP_KERNEL|__GFP_ZERO node=-1 accounted=false 4582.696653: kmem_cache_free: call_site=do_sys_openat2+0xa7/0xd0 ptr=00000000e70e10e0 name=names_cache But when printing via print_fields() (echo 1 > /sys/kernel/tracing/options/fields) the same event output looks like this: 4582.696626: kmem_cache_alloc: call_site=0xffffffff92d10d97 (-1831793257) ptr=0xffff9e0e8571e000 (-107689771147264) bytes_req=0x1000 (4096) bytes_alloc=0x1000 (4096) gfp_flags=0xcc0 (3264) node=0xffffffff (-1) accounted=(0) 4582.696629: kmem_cache_alloc: call_site=0xffffffff92d0250b (-1831852789) ptr=0xffff9e0e8577f800 (-107689770747904) bytes_req=0x168 (360) bytes_alloc=0x180 (384) gfp_flags=0xcc0 (3264) node=0xffffffff (-1) accounted=(0) 4582.696630: kmem_cache_alloc: call_site=0xffffffff92efca74 (-1829778828) ptr=0xffff9e0e8d35d3b0 (-107689640864848) bytes_req=0x10 (16) bytes_alloc=0x10 (16) gfp_flags=0xdc0 (3520) node=0xffffffff (-1) accounted=(0) 4582.696653: kmem_cache_free: call_site=0xffffffff92cfbea7 (-1831879001) ptr=0xffff9e0e8571e000 (-107689771147264) name=names_cache Cc: stable@vger.kernel.org Cc: Masami Hiramatsu Cc: Mathieu Desnoyers Cc: Linus Torvalds Link: https://lore.kernel.org/20241218141507.28389a1d@gandalf.local.home Fixes: 07714b4bb3f98 ("tracing: Handle old buffer mappings for event strings and functions") Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace.c | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'kernel') diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index be62f0ea1814..6581cb2bc67f 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -4353,6 +4353,15 @@ static enum print_line_t print_trace_fmt(struct trace_iterator *iter) if (event) { if (tr->trace_flags & TRACE_ITER_FIELDS) return print_event_fields(iter, event); + /* + * For TRACE_EVENT() events, the print_fmt is not + * safe to use if the array has delta offsets + * Force printing via the fields. + */ + if ((tr->text_delta || tr->data_delta) && + event->type > __TRACE_LAST_TYPE) + return print_event_fields(iter, event); + return event->funcs->trace(iter, sym_flags, event); } -- cgit v1.2.3 From 8ac662f5da19f5873fdd94c48a5cdb45b2e1b58f Mon Sep 17 00:00:00 2001 From: Lorenzo Stoakes Date: Tue, 10 Dec 2024 17:24:12 +0000 Subject: fork: avoid inappropriate uprobe access to invalid mm If dup_mmap() encounters an issue, currently uprobe is able to access the relevant mm via the reverse mapping (in build_map_info()), and if we are very unlucky with a race window, observe invalid XA_ZERO_ENTRY state which we establish as part of the fork error path. This occurs because uprobe_write_opcode() invokes anon_vma_prepare() which in turn invokes find_mergeable_anon_vma() that uses a VMA iterator, invoking vma_iter_load() which uses the advanced maple tree API and thus is able to observe XA_ZERO_ENTRY entries added to dup_mmap() in commit d24062914837 ("fork: use __mt_dup() to duplicate maple tree in dup_mmap()"). This change was made on the assumption that only process tear-down code would actually observe (and make use of) these values. However this very unlikely but still possible edge case with uprobes exists and unfortunately does make these observable. The uprobe operation prevents races against the dup_mmap() operation via the dup_mmap_sem semaphore, which is acquired via uprobe_start_dup_mmap() and dropped via uprobe_end_dup_mmap(), and held across register_for_each_vma() prior to invoking build_map_info() which does the reverse mapping lookup. Currently these are acquired and dropped within dup_mmap(), which exposes the race window prior to error handling in the invoking dup_mm() which tears down the mm. We can avoid all this by just moving the invocation of uprobe_start_dup_mmap() and uprobe_end_dup_mmap() up a level to dup_mm() and only release this lock once the dup_mmap() operation succeeds or clean up is done. This means that the uprobe code can never observe an incompletely constructed mm and resolves the issue in this case. Link: https://lkml.kernel.org/r/20241210172412.52995-1-lorenzo.stoakes@oracle.com Fixes: d24062914837 ("fork: use __mt_dup() to duplicate maple tree in dup_mmap()") Signed-off-by: Lorenzo Stoakes Reported-by: syzbot+2d788f4f7cb660dac4b7@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/6756d273.050a0220.2477f.003d.GAE@google.com/ Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Arnaldo Carvalho de Melo Cc: Ian Rogers Cc: Ingo Molnar Cc: Jann Horn Cc: Jiri Olsa Cc: Kan Liang Cc: Liam R. Howlett Cc: Mark Rutland Cc: Masami Hiramatsu Cc: Namhyung Kim Cc: Oleg Nesterov Cc: Peng Zhang Cc: Peter Zijlstra Cc: Vlastimil Babka Cc: David Hildenbrand Signed-off-by: Andrew Morton --- kernel/fork.c | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-) (limited to 'kernel') diff --git a/kernel/fork.c b/kernel/fork.c index 1450b461d196..9b301180fd41 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -639,11 +639,8 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm, LIST_HEAD(uf); VMA_ITERATOR(vmi, mm, 0); - uprobe_start_dup_mmap(); - if (mmap_write_lock_killable(oldmm)) { - retval = -EINTR; - goto fail_uprobe_end; - } + if (mmap_write_lock_killable(oldmm)) + return -EINTR; flush_cache_dup_mm(oldmm); uprobe_dup_mmap(oldmm, mm); /* @@ -782,8 +779,6 @@ out: dup_userfaultfd_complete(&uf); else dup_userfaultfd_fail(&uf); -fail_uprobe_end: - uprobe_end_dup_mmap(); return retval; fail_nomem_anon_vma_fork: @@ -1692,9 +1687,11 @@ static struct mm_struct *dup_mm(struct task_struct *tsk, if (!mm_init(mm, tsk, mm->user_ns)) goto fail_nomem; + uprobe_start_dup_mmap(); err = dup_mmap(mm, oldmm); if (err) goto free_pt; + uprobe_end_dup_mmap(); mm->hiwater_rss = get_mm_rss(mm); mm->hiwater_vm = mm->total_vm; @@ -1709,6 +1706,8 @@ free_pt: mm->binfmt = NULL; mm_init_owner(mm, NULL); mmput(mm); + if (err) + uprobe_end_dup_mmap(); fail_nomem: return NULL; -- cgit v1.2.3 From de35994ecd2dd6148ab5a6c5050a1670a04dec77 Mon Sep 17 00:00:00 2001 From: Tvrtko Ursulin Date: Thu, 19 Dec 2024 09:30:30 +0000 Subject: workqueue: Do not warn when cancelling WQ_MEM_RECLAIM work from !WQ_MEM_RECLAIM worker MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit After commit 746ae46c1113 ("drm/sched: Mark scheduler work queues with WQ_MEM_RECLAIM") amdgpu started seeing the following warning: [ ] workqueue: WQ_MEM_RECLAIM sdma0:drm_sched_run_job_work [gpu_sched] is flushing !WQ_MEM_RECLAIM events:amdgpu_device_delay_enable_gfx_off [amdgpu] ... [ ] Workqueue: sdma0 drm_sched_run_job_work [gpu_sched] ... [ ] Call Trace: [ ] ... [ ] ? check_flush_dependency+0xf5/0x110 ... [ ] cancel_delayed_work_sync+0x6e/0x80 [ ] amdgpu_gfx_off_ctrl+0xab/0x140 [amdgpu] [ ] amdgpu_ring_alloc+0x40/0x50 [amdgpu] [ ] amdgpu_ib_schedule+0xf4/0x810 [amdgpu] [ ] ? drm_sched_run_job_work+0x22c/0x430 [gpu_sched] [ ] amdgpu_job_run+0xaa/0x1f0 [amdgpu] [ ] drm_sched_run_job_work+0x257/0x430 [gpu_sched] [ ] process_one_work+0x217/0x720 ... [ ] The intent of the verifcation done in check_flush_depedency is to ensure forward progress during memory reclaim, by flagging cases when either a memory reclaim process, or a memory reclaim work item is flushed from a context not marked as memory reclaim safe. This is correct when flushing, but when called from the cancel(_delayed)_work_sync() paths it is a false positive because work is either already running, or will not be running at all. Therefore cancelling it is safe and we can relax the warning criteria by letting the helper know of the calling context. Signed-off-by: Tvrtko Ursulin Fixes: fca839c00a12 ("workqueue: warn if memory reclaim tries to flush !WQ_MEM_RECLAIM workqueue") References: 746ae46c1113 ("drm/sched: Mark scheduler work queues with WQ_MEM_RECLAIM") Cc: Tejun Heo Cc: Peter Zijlstra Cc: Lai Jiangshan Cc: Alex Deucher Cc: Christian König Cc: # v4.5+ Signed-off-by: Tejun Heo --- kernel/workqueue.c | 22 +++++++++++++--------- 1 file changed, 13 insertions(+), 9 deletions(-) (limited to 'kernel') diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 8b07576814a5..8336218ec4b8 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -3680,23 +3680,27 @@ void workqueue_softirq_dead(unsigned int cpu) * check_flush_dependency - check for flush dependency sanity * @target_wq: workqueue being flushed * @target_work: work item being flushed (NULL for workqueue flushes) + * @from_cancel: are we called from the work cancel path * * %current is trying to flush the whole @target_wq or @target_work on it. - * If @target_wq doesn't have %WQ_MEM_RECLAIM, verify that %current is not - * reclaiming memory or running on a workqueue which doesn't have - * %WQ_MEM_RECLAIM as that can break forward-progress guarantee leading to - * a deadlock. + * If this is not the cancel path (which implies work being flushed is either + * already running, or will not be at all), check if @target_wq doesn't have + * %WQ_MEM_RECLAIM and verify that %current is not reclaiming memory or running + * on a workqueue which doesn't have %WQ_MEM_RECLAIM as that can break forward- + * progress guarantee leading to a deadlock. */ static void check_flush_dependency(struct workqueue_struct *target_wq, - struct work_struct *target_work) + struct work_struct *target_work, + bool from_cancel) { - work_func_t target_func = target_work ? target_work->func : NULL; + work_func_t target_func; struct worker *worker; - if (target_wq->flags & WQ_MEM_RECLAIM) + if (from_cancel || target_wq->flags & WQ_MEM_RECLAIM) return; worker = current_wq_worker(); + target_func = target_work ? target_work->func : NULL; WARN_ONCE(current->flags & PF_MEMALLOC, "workqueue: PF_MEMALLOC task %d(%s) is flushing !WQ_MEM_RECLAIM %s:%ps", @@ -3980,7 +3984,7 @@ void __flush_workqueue(struct workqueue_struct *wq) list_add_tail(&this_flusher.list, &wq->flusher_overflow); } - check_flush_dependency(wq, NULL); + check_flush_dependency(wq, NULL, false); mutex_unlock(&wq->mutex); @@ -4155,7 +4159,7 @@ static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr, } wq = pwq->wq; - check_flush_dependency(wq, work); + check_flush_dependency(wq, work, from_cancel); insert_wq_barrier(pwq, barr, work, worker); raw_spin_unlock_irq(&pool->lock); -- cgit v1.2.3 From d685d55dfc86b1a4bdcec77c3c1f8a83f181264e Mon Sep 17 00:00:00 2001 From: "Masami Hiramatsu (Google)" Date: Wed, 11 Dec 2024 09:10:55 +0900 Subject: tracing/kprobe: Make trace_kprobe's module callback called after jump_label update Make sure the trace_kprobe's module notifer callback function is called after jump_label's callback is called. Since the trace_kprobe's callback eventually checks jump_label address during registering new kprobe on the loading module, jump_label must be updated before this registration happens. Link: https://lore.kernel.org/all/173387585556.995044.3157941002975446119.stgit@devnote2/ Fixes: 614243181050 ("tracing/kprobes: Support module init function probing") Signed-off-by: Masami Hiramatsu (Google) --- kernel/trace/trace_kprobe.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c index 263fac44d3ca..935a886af40c 100644 --- a/kernel/trace/trace_kprobe.c +++ b/kernel/trace/trace_kprobe.c @@ -725,7 +725,7 @@ static int trace_kprobe_module_callback(struct notifier_block *nb, static struct notifier_block trace_kprobe_module_nb = { .notifier_call = trace_kprobe_module_callback, - .priority = 1 /* Invoked after kprobe module callback */ + .priority = 2 /* Invoked after kprobe and jump_label module callback */ }; static int trace_kprobe_register_module_notifier(void) { -- cgit v1.2.3 From 98feccbf32cfdde8c722bc4587aaa60ee5ac33f0 Mon Sep 17 00:00:00 2001 From: Lizhi Xu Date: Mon, 16 Dec 2024 15:32:38 +0800 Subject: tracing: Prevent bad count for tracing_cpumask_write If a large count is provided, it will trigger a warning in bitmap_parse_user. Also check zero for it. Cc: stable@vger.kernel.org Fixes: 9e01c1b74c953 ("cpumask: convert kernel trace functions") Link: https://lore.kernel.org/20241216073238.2573704-1-lizhi.xu@windriver.com Reported-by: syzbot+0aecfd34fb878546f3fd@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=0aecfd34fb878546f3fd Tested-by: syzbot+0aecfd34fb878546f3fd@syzkaller.appspotmail.com Signed-off-by: Lizhi Xu Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'kernel') diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 957f941a08e7..f8aebcb01e62 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -5087,6 +5087,9 @@ tracing_cpumask_write(struct file *filp, const char __user *ubuf, cpumask_var_t tracing_cpumask_new; int err; + if (count == 0 || count > KMALLOC_MAX_SIZE) + return -EINVAL; + if (!zalloc_cpumask_var(&tracing_cpumask_new, GFP_KERNEL)) return -ENOMEM; -- cgit v1.2.3 From d57212f281fda9056412cd6cca983d9d2eb89f53 Mon Sep 17 00:00:00 2001 From: Su Hui Date: Tue, 24 Dec 2024 12:43:58 +0800 Subject: workqueue: add printf attribute to __alloc_workqueue() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Fix a compiler warning with W=1: kernel/workqueue.c: error: function ‘__alloc_workqueue’ might be a candidate for ‘gnu_printf’ format attribute[-Werror=suggest-attribute=format] 5657 | name_len = vsnprintf(wq->name, sizeof(wq->name), fmt, args); | ^~~~~~~~ Fixes: 9b59a85a84dc ("workqueue: Don't call va_start / va_end twice") Signed-off-by: Su Hui Signed-off-by: Tejun Heo --- kernel/workqueue.c | 1 + 1 file changed, 1 insertion(+) (limited to 'kernel') diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 8336218ec4b8..f7d8fc204579 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -5645,6 +5645,7 @@ static void wq_adjust_max_active(struct workqueue_struct *wq) } while (activated); } +__printf(1, 0) static struct workqueue_struct *__alloc_workqueue(const char *fmt, unsigned int flags, int max_active, va_list args) -- cgit v1.2.3 From 35bf430e08a18fdab6eb94492a06d9ad14c6179b Mon Sep 17 00:00:00 2001 From: Henry Huang Date: Sun, 22 Dec 2024 23:43:16 +0800 Subject: sched_ext: initialize kit->cursor.flags struct bpf_iter_scx_dsq *it maybe not initialized. If we didn't call scx_bpf_dsq_move_set_vtime and scx_bpf_dsq_move_set_slice before scx_bpf_dsq_move, it would cause unexpected behaviors: 1. Assign a huge slice into p->scx.slice 2. Assign a invalid vtime into p->scx.dsq_vtime Signed-off-by: Henry Huang Fixes: 6462dd53a260 ("sched_ext: Compact struct bpf_iter_scx_dsq_kern") Cc: stable@vger.kernel.org # v6.12 Signed-off-by: Tejun Heo --- kernel/sched/ext.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c index 98519e6d0dcd..19d2699cf638 100644 --- a/kernel/sched/ext.c +++ b/kernel/sched/ext.c @@ -7013,7 +7013,7 @@ __bpf_kfunc int bpf_iter_scx_dsq_new(struct bpf_iter_scx_dsq *it, u64 dsq_id, return -ENOENT; INIT_LIST_HEAD(&kit->cursor.node); - kit->cursor.flags |= SCX_DSQ_LNODE_ITER_CURSOR | flags; + kit->cursor.flags = SCX_DSQ_LNODE_ITER_CURSOR | flags; kit->cursor.priv = READ_ONCE(kit->dsq->seq); return 0; -- cgit v1.2.3 From cb0ca08b326aa03f87fe94bb91872ce8d2ef1ed8 Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Tue, 17 Dec 2024 08:18:10 +0100 Subject: kcov: mark in_softirq_really() as __always_inline If gcc decides not to inline in_softirq_really(), objtool warns about a function call with UACCESS enabled: kernel/kcov.o: warning: objtool: __sanitizer_cov_trace_pc+0x1e: call to in_softirq_really() with UACCESS enabled kernel/kcov.o: warning: objtool: check_kcov_mode+0x11: call to in_softirq_really() with UACCESS enabled Mark this as __always_inline to avoid the problem. Link: https://lkml.kernel.org/r/20241217071814.2261620-1-arnd@kernel.org Fixes: 7d4df2dad312 ("kcov: properly check for softirq context") Signed-off-by: Arnd Bergmann Reviewed-by: Marco Elver Cc: Aleksandr Nogikh Cc: Andrey Konovalov Cc: Dmitry Vyukov Cc: Josh Poimboeuf Cc: Peter Zijlstra Cc: Signed-off-by: Andrew Morton --- kernel/kcov.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/kcov.c b/kernel/kcov.c index 28a6be6e64fd..187ba1b80bda 100644 --- a/kernel/kcov.c +++ b/kernel/kcov.c @@ -166,7 +166,7 @@ static void kcov_remote_area_put(struct kcov_remote_area *area, * Unlike in_serving_softirq(), this function returns false when called during * a hardirq or an NMI that happened in the softirq context. */ -static inline bool in_softirq_really(void) +static __always_inline bool in_softirq_really(void) { return in_serving_softirq() && !in_hardirq() && !in_nmi(); } -- cgit v1.2.3 From afc6717628f959941d7b33728570568b4af1c4b8 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Tue, 31 Dec 2024 00:06:46 -0500 Subject: tracing: Have process_string() also allow arrays In order to catch a common bug where a TRACE_EVENT() TP_fast_assign() assigns an address of an allocated string to the ring buffer and then references it in TP_printk(), which can be executed hours later when the string is free, the function test_event_printk() runs on all events as they are registered to make sure there's no unwanted dereferencing. It calls process_string() to handle cases in TP_printk() format that has "%s". It returns whether or not the string is safe. But it can have some false positives. For instance, xe_bo_move() has: TP_printk("move_lacks_source:%s, migrate object %p [size %zu] from %s to %s device_id:%s", __entry->move_lacks_source ? "yes" : "no", __entry->bo, __entry->size, xe_mem_type_to_name[__entry->old_placement], xe_mem_type_to_name[__entry->new_placement], __get_str(device_id)) Where the "%s" references into xe_mem_type_to_name[]. This is an array of pointers that should be safe for the event to access. Instead of flagging this as a bad reference, if a reference points to an array, where the record field is the index, consider it safe. Link: https://lore.kernel.org/all/9dee19b6185d325d0e6fa5f7cbba81d007d99166.camel@sapience.com/ Cc: stable@vger.kernel.org Cc: Masami Hiramatsu Cc: Mathieu Desnoyers Link: https://lore.kernel.org/20241231000646.324fb5f7@gandalf.local.home Fixes: 65a25d9f7ac02 ("tracing: Add "%s" check in test_event_printk()") Reported-by: Genes Lists Tested-by: Gene C Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace_events.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) (limited to 'kernel') diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index 1545cc8b49d0..770e7ed91716 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -364,6 +364,18 @@ static bool process_string(const char *fmt, int len, struct trace_event_call *ca s = r + 1; } while (s < e); + /* + * Check for arrays. If the argument has: foo[REC->val] + * then it is very likely that foo is an array of strings + * that are safe to use. + */ + r = strstr(s, "["); + if (r && r < e) { + r = strstr(r, "REC->"); + if (r && r < e) + return true; + } + /* * If there's any strings in the argument consider this arg OK as it * could be: REC->field ? "foo" : "bar" and we don't want to get into -- cgit v1.2.3 From d65474033740ded0a4fe9a097fce72328655b41d Mon Sep 17 00:00:00 2001 From: Zilin Guan Date: Tue, 31 Dec 2024 11:37:31 +0000 Subject: fgraph: Add READ_ONCE() when accessing fgraph_array[] In __ftrace_return_to_handler(), a loop iterates over the fgraph_array[] elements, which are fgraph_ops. The loop checks if an element is a fgraph_stub to prevent using a fgraph_stub afterward. However, if the compiler reloads fgraph_array[] after this check, it might race with an update to fgraph_array[] that introduces a fgraph_stub. This could result in the stub being processed, but the stub contains a null "func_hash" field, leading to a NULL pointer dereference. To ensure that the gops compared against the fgraph_stub matches the gops processed later, add a READ_ONCE(). A similar patch appears in commit 63a8dfb ("function_graph: Add READ_ONCE() when accessing fgraph_array[]"). Cc: stable@vger.kernel.org Fixes: 37238abe3cb47 ("ftrace/function_graph: Pass fgraph_ops to function graph callbacks") Link: https://lore.kernel.org/20241231113731.277668-1-zilin@seu.edu.cn Signed-off-by: Zilin Guan Signed-off-by: Steven Rostedt (Google) --- kernel/trace/fgraph.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c index ddedcb50917f..30e3ddc8a8a8 100644 --- a/kernel/trace/fgraph.c +++ b/kernel/trace/fgraph.c @@ -833,7 +833,7 @@ static unsigned long __ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs #endif { for_each_set_bit(i, &bitmap, sizeof(bitmap) * BITS_PER_BYTE) { - struct fgraph_ops *gops = fgraph_array[i]; + struct fgraph_ops *gops = READ_ONCE(fgraph_array[i]); if (gops == &fgraph_stub) continue; -- cgit v1.2.3 From 789a8cff8d2dbe4b5c617c3004b5eb63fa7a3b35 Mon Sep 17 00:00:00 2001 From: Kohei Enju Date: Thu, 2 Jan 2025 04:08:20 +0900 Subject: ftrace: Fix function profiler's filtering functionality Commit c132be2c4fcc ("function_graph: Have the instances use their own ftrace_ops for filtering"), function profiler (enabled via function_profile_enabled) has been showing statistics for all functions, ignoring set_ftrace_filter settings. While tracers are instantiated, the function profiler is not. Therefore, it should use the global set_ftrace_filter for consistency. This patch modifies the function profiler to use the global filter, fixing the filtering functionality. Before (filtering not working): ``` root@localhost:~# echo 'vfs*' > /sys/kernel/tracing/set_ftrace_filter root@localhost:~# echo 1 > /sys/kernel/tracing/function_profile_enabled root@localhost:~# sleep 1 root@localhost:~# echo 0 > /sys/kernel/tracing/function_profile_enabled root@localhost:~# head /sys/kernel/tracing/trace_stat/* Function Hit Time Avg s^2 -------- --- ---- --- --- schedule 314 22290594 us 70989.15 us 40372231 us x64_sys_call 1527 8762510 us 5738.382 us 3414354 us schedule_hrtimeout_range 176 8665356 us 49234.98 us 405618876 us __x64_sys_ppoll 324 5656635 us 17458.75 us 19203976 us do_sys_poll 324 5653747 us 17449.83 us 19214945 us schedule_timeout 67 5531396 us 82558.15 us 2136740827 us __x64_sys_pselect6 12 3029540 us 252461.7 us 63296940171 us do_pselect.constprop.0 12 3029532 us 252461.0 us 63296952931 us ``` After (filtering working): ``` root@localhost:~# echo 'vfs*' > /sys/kernel/tracing/set_ftrace_filter root@localhost:~# echo 1 > /sys/kernel/tracing/function_profile_enabled root@localhost:~# sleep 1 root@localhost:~# echo 0 > /sys/kernel/tracing/function_profile_enabled root@localhost:~# head /sys/kernel/tracing/trace_stat/* Function Hit Time Avg s^2 -------- --- ---- --- --- vfs_write 462 68476.43 us 148.217 us 25874.48 us vfs_read 641 9611.356 us 14.994 us 28868.07 us vfs_fstat 890 878.094 us 0.986 us 1.667 us vfs_fstatat 227 757.176 us 3.335 us 18.928 us vfs_statx 226 610.610 us 2.701 us 17.749 us vfs_getattr_nosec 1187 460.919 us 0.388 us 0.326 us vfs_statx_path 297 343.287 us 1.155 us 11.116 us vfs_rename 6 291.575 us 48.595 us 9889.236 us ``` Cc: stable@vger.kernel.org Link: https://lore.kernel.org/20250101190820.72534-1-enjuk@amazon.com Fixes: c132be2c4fcc ("function_graph: Have the instances use their own ftrace_ops for filtering") Signed-off-by: Kohei Enju Signed-off-by: Steven Rostedt (Google) --- kernel/trace/ftrace.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) (limited to 'kernel') diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 9b17efb1a87d..2e113f8b13a2 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -902,16 +902,13 @@ static void profile_graph_return(struct ftrace_graph_ret *trace, } static struct fgraph_ops fprofiler_ops = { - .ops = { - .flags = FTRACE_OPS_FL_INITIALIZED, - INIT_OPS_HASH(fprofiler_ops.ops) - }, .entryfunc = &profile_graph_entry, .retfunc = &profile_graph_return, }; static int register_ftrace_profiler(void) { + ftrace_ops_set_global_filter(&fprofiler_ops.ops); return register_ftrace_graph(&fprofiler_ops); } @@ -922,12 +919,11 @@ static void unregister_ftrace_profiler(void) #else static struct ftrace_ops ftrace_profile_ops __read_mostly = { .func = function_profile_call, - .flags = FTRACE_OPS_FL_INITIALIZED, - INIT_OPS_HASH(ftrace_profile_ops) }; static int register_ftrace_profiler(void) { + ftrace_ops_set_global_filter(&ftrace_profile_ops); return register_ftrace_function(&ftrace_profile_ops); } -- cgit v1.2.3