linux-toradex.git/kernel/trace/trace_events_hist.c, branch v6.13 Linux kernel for Apalis and Colibri modules tracing: Remove redundant check on field->field in histograms 2024-11-12T16:36:57+00:00 Colin Ian King colin.i.king@gmail.com 2024-11-07T12:05:30+00:00 6371b4bc179aad17d84ee301b409a5a8ce675657 The check on field->field being true is handled as the first check on the cascaded if statement, so the later checks on field->field are redundant because this clause has already been handled. Since this later check is redundant, just remove it. Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Link: https://lore.kernel.org/20241107120530.18728-1-colin.i.king@gmail.com Signed-off-by: Colin Ian King <colin.i.king@gmail.com> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> 
The check on field->field being true is handled as the first check
on the cascaded if statement, so the later checks on field->field
are redundant because this clause has already been handled. Since
this later check is redundant, just remove it.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/20241107120530.18728-1-colin.i.king@gmail.com
Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
tracing: Replace strncpy() with strscpy() when copying comm 2024-11-01T18:37:31+00:00 Jinjie Ruan ruanjinjie@huawei.com 2024-10-31T12:01:39+00:00 242b32d8073ed16868ff0f9381732e9782dea63b Replace the depreciated[1] strncpy() calls with strscpy() when copying comm. Link: https://github.com/KSPP/linux/issues/90 [1] Cc: <mhiramat@kernel.org> Cc: <mathieu.desnoyers@efficios.com> Link: https://lore.kernel.org/20241031120139.1343025-1-ruanjinjie@huawei.com Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> 
Replace the depreciated[1] strncpy() calls with strscpy()
when copying comm.

Link: https://github.com/KSPP/linux/issues/90 [1]

Cc: <mhiramat@kernel.org>
Cc: <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/20241031120139.1343025-1-ruanjinjie@huawei.com
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
tracepoints: Use new static branch API 2024-10-09T01:17:39+00:00 Josh Poimboeuf jpoimboe@kernel.org 2024-10-08T19:17:19+00:00 4a8840af5f53f2902eba91130fae650879f18e7a The old static key API is deprecated. Switch to the new one. Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Alice Ryhl <aliceryhl@google.com> Link: https://lore.kernel.org/7a08dae3c5eddb14b13864923c1b58ac1f4af83c.1728414936.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> 
The old static key API is deprecated.  Switch to the new one.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/7a08dae3c5eddb14b13864923c1b58ac1f4af83c.1728414936.git.jpoimboe@kernel.org
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
tracing: Have format file honor EVENT_FILE_FL_FREED 2024-08-07T22:12:46+00:00 Steven Rostedt rostedt@goodmis.org 2024-07-30T15:06:57+00:00 b1560408692cd0ab0370cfbe9deb03ce97ab3f6d When eventfs was introduced, special care had to be done to coordinate the freeing of the file meta data with the files that are exposed to user space. The file meta data would have a ref count that is set when the file is created and would be decremented and freed after the last user that opened the file closed it. When the file meta data was to be freed, it would set a flag (EVENT_FILE_FL_FREED) to denote that the file is freed, and any new references made (like new opens or reads) would fail as it is marked freed. This allowed other meta data to be freed after this flag was set (under the event_mutex). All the files that were dynamically created in the events directory had a pointer to the file meta data and would call event_release() when the last reference to the user space file was closed. This would be the time that it is safe to free the file meta data. A shortcut was made for the "format" file. It's i_private would point to the "call" entry directly and not point to the file's meta data. This is because all format files are the same for the same "call", so it was thought there was no reason to differentiate them. The other files maintain state (like the "enable", "trigger", etc). But this meant if the file were to disappear, the "format" file would be unaware of it. This caused a race that could be trigger via the user_events test (that would create dynamic events and free them), and running a loop that would read the user_events format files: In one console run: # cd tools/testing/selftests/user_events # while true; do ./ftrace_test; done And in another console run: # cd /sys/kernel/tracing/ # while true; do cat events/user_events/__test_event/format; done 2>/dev/null With KASAN memory checking, it would trigger a use-after-free bug report (which was a real bug). This was because the format file was not checking the file's meta data flag "EVENT_FILE_FL_FREED", so it would access the event that the file meta data pointed to after the event was freed. After inspection, there are other locations that were found to not check the EVENT_FILE_FL_FREED flag when accessing the trace_event_file. Add a new helper function: event_file_file() that will make sure that the event_mutex is held, and will return NULL if the trace_event_file has the EVENT_FILE_FL_FREED flag set. Have the first reference of the struct file pointer use event_file_file() and check for NULL. Later uses can still use the event_file_data() helper function if the event_mutex is still held and was not released since the event_file_file() call. Link: https://lore.kernel.org/all/20240719204701.1605950-1-minipli@grsecurity.net/ Cc: stable@vger.kernel.org Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Ajay Kaher <ajay.kaher@broadcom.com> Cc: Ilkka Naulapää <digirigawa@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Dan Carpenter <dan.carpenter@linaro.org> Cc: Beau Belgrave <beaub@linux.microsoft.com> Cc: Florian Fainelli <florian.fainelli@broadcom.com> Cc: Alexey Makhalov <alexey.makhalov@broadcom.com> Cc: Vasavi Sirnapalli <vasavi.sirnapalli@broadcom.com> Link: https://lore.kernel.org/20240730110657.3b69d3c1@gandalf.local.home Fixes: b63db58e2fa5d ("eventfs/tracing: Add callback for release of an eventfs_inode") Reported-by: Mathias Krause <minipli@grsecurity.net> Tested-by: Mathias Krause <minipli@grsecurity.net> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> 
When eventfs was introduced, special care had to be done to coordinate the
freeing of the file meta data with the files that are exposed to user
space. The file meta data would have a ref count that is set when the file
is created and would be decremented and freed after the last user that
opened the file closed it. When the file meta data was to be freed, it
would set a flag (EVENT_FILE_FL_FREED) to denote that the file is freed,
and any new references made (like new opens or reads) would fail as it is
marked freed. This allowed other meta data to be freed after this flag was
set (under the event_mutex).

All the files that were dynamically created in the events directory had a
pointer to the file meta data and would call event_release() when the last
reference to the user space file was closed. This would be the time that it
is safe to free the file meta data.

A shortcut was made for the "format" file. It's i_private would point to
the "call" entry directly and not point to the file's meta data. This is
because all format files are the same for the same "call", so it was
thought there was no reason to differentiate them.  The other files
maintain state (like the "enable", "trigger", etc). But this meant if the
file were to disappear, the "format" file would be unaware of it.

This caused a race that could be trigger via the user_events test (that
would create dynamic events and free them), and running a loop that would
read the user_events format files:

In one console run:

 # cd tools/testing/selftests/user_events
 # while true; do ./ftrace_test; done

And in another console run:

 # cd /sys/kernel/tracing/
 # while true; do cat events/user_events/__test_event/format; done 2>/dev/null

With KASAN memory checking, it would trigger a use-after-free bug report
(which was a real bug). This was because the format file was not checking
the file's meta data flag "EVENT_FILE_FL_FREED", so it would access the
event that the file meta data pointed to after the event was freed.

After inspection, there are other locations that were found to not check
the EVENT_FILE_FL_FREED flag when accessing the trace_event_file. Add a
new helper function: event_file_file() that will make sure that the
event_mutex is held, and will return NULL if the trace_event_file has the
EVENT_FILE_FL_FREED flag set. Have the first reference of the struct file
pointer use event_file_file() and check for NULL. Later uses can still use
the event_file_data() helper function if the event_mutex is still held and
was not released since the event_file_file() call.

Link: https://lore.kernel.org/all/20240719204701.1605950-1-minipli@grsecurity.net/

Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers   <mathieu.desnoyers@efficios.com>
Cc: Ajay Kaher <ajay.kaher@broadcom.com>
Cc: Ilkka Naulapää    <digirigawa@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Al   Viro <viro@zeniv.linux.org.uk>
Cc: Dan Carpenter   <dan.carpenter@linaro.org>
Cc: Beau Belgrave <beaub@linux.microsoft.com>
Cc: Florian Fainelli  <florian.fainelli@broadcom.com>
Cc: Alexey Makhalov    <alexey.makhalov@broadcom.com>
Cc: Vasavi Sirnapalli    <vasavi.sirnapalli@broadcom.com>
Link: https://lore.kernel.org/20240730110657.3b69d3c1@gandalf.local.home
Fixes: b63db58e2fa5d ("eventfs/tracing: Add callback for release of an eventfs_inode")
Reported-by: Mathias Krause <minipli@grsecurity.net>
Tested-by: Mathias Krause <minipli@grsecurity.net>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
tracing histograms: Simplify parse_actions() function 2024-01-08T18:24:56+00:00 Steven Rostedt (Google) rostedt@goodmis.org 2024-01-08T01:32:58+00:00 4f1991a92cfe89096b2d1f5583a2e093bdd55c37 The parse_actions() function uses 'len = str_has_prefix()' to test which action is in the string being parsed. But then it goes and repeats the logic for each different action. This logic can be simplified and duplicate code can be removed as 'len' contains the length of the found prefix which should be used for all actions. Link: https://lore.kernel.org/all/20240107112044.6702cb66@gandalf.local.home/ Link: https://lore.kernel.org/linux-trace-kernel/20240107203258.37e26d2b@gandalf.local.home Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Andy Shevchenko <andy@kernel.org> Cc: Tom Zanussi <zanussi@kernel.org> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> 
The parse_actions() function uses 'len = str_has_prefix()' to test which
action is in the string being parsed. But then it goes and repeats the
logic for each different action. This logic can be simplified and
duplicate code can be removed as 'len' contains the length of the found
prefix which should be used for all actions.

Link: https://lore.kernel.org/all/20240107112044.6702cb66@gandalf.local.home/
Link: https://lore.kernel.org/linux-trace-kernel/20240107203258.37e26d2b@gandalf.local.home

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andy Shevchenko <andy@kernel.org>
Cc: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
tracing: Fix uaf issue when open the hist or hist_debug file 2023-12-14T04:29:59+00:00 Zheng Yejian zhengyejian1@huawei.com 2023-12-14T01:21:53+00:00 1cc111b9cddc71ce161cd388f11f0e9048edffdb KASAN report following issue. The root cause is when opening 'hist' file of an instance and accessing 'trace_event_file' in hist_show(), but 'trace_event_file' has been freed due to the instance being removed. 'hist_debug' file has the same problem. To fix it, call tracing_{open,release}_file_tr() in file_operations callback to have the ref count and avoid 'trace_event_file' being freed. BUG: KASAN: slab-use-after-free in hist_show+0x11e0/0x1278 Read of size 8 at addr ffff242541e336b8 by task head/190 CPU: 4 PID: 190 Comm: head Not tainted 6.7.0-rc5-g26aff849438c #133 Hardware name: linux,dummy-virt (DT) Call trace: dump_backtrace+0x98/0xf8 show_stack+0x1c/0x30 dump_stack_lvl+0x44/0x58 print_report+0xf0/0x5a0 kasan_report+0x80/0xc0 __asan_report_load8_noabort+0x1c/0x28 hist_show+0x11e0/0x1278 seq_read_iter+0x344/0xd78 seq_read+0x128/0x1c0 vfs_read+0x198/0x6c8 ksys_read+0xf4/0x1e0 __arm64_sys_read+0x70/0xa8 invoke_syscall+0x70/0x260 el0_svc_common.constprop.0+0xb0/0x280 do_el0_svc+0x44/0x60 el0_svc+0x34/0x68 el0t_64_sync_handler+0xb8/0xc0 el0t_64_sync+0x168/0x170 Allocated by task 188: kasan_save_stack+0x28/0x50 kasan_set_track+0x28/0x38 kasan_save_alloc_info+0x20/0x30 __kasan_slab_alloc+0x6c/0x80 kmem_cache_alloc+0x15c/0x4a8 trace_create_new_event+0x84/0x348 __trace_add_new_event+0x18/0x88 event_trace_add_tracer+0xc4/0x1a0 trace_array_create_dir+0x6c/0x100 trace_array_create+0x2e8/0x568 instance_mkdir+0x48/0x80 tracefs_syscall_mkdir+0x90/0xe8 vfs_mkdir+0x3c4/0x610 do_mkdirat+0x144/0x200 __arm64_sys_mkdirat+0x8c/0xc0 invoke_syscall+0x70/0x260 el0_svc_common.constprop.0+0xb0/0x280 do_el0_svc+0x44/0x60 el0_svc+0x34/0x68 el0t_64_sync_handler+0xb8/0xc0 el0t_64_sync+0x168/0x170 Freed by task 191: kasan_save_stack+0x28/0x50 kasan_set_track+0x28/0x38 kasan_save_free_info+0x34/0x58 __kasan_slab_free+0xe4/0x158 kmem_cache_free+0x19c/0x508 event_file_put+0xa0/0x120 remove_event_file_dir+0x180/0x320 event_trace_del_tracer+0xb0/0x180 __remove_instance+0x224/0x508 instance_rmdir+0x44/0x78 tracefs_syscall_rmdir+0xbc/0x140 vfs_rmdir+0x1cc/0x4c8 do_rmdir+0x220/0x2b8 __arm64_sys_unlinkat+0xc0/0x100 invoke_syscall+0x70/0x260 el0_svc_common.constprop.0+0xb0/0x280 do_el0_svc+0x44/0x60 el0_svc+0x34/0x68 el0t_64_sync_handler+0xb8/0xc0 el0t_64_sync+0x168/0x170 Link: https://lore.kernel.org/linux-trace-kernel/20231214012153.676155-1-zhengyejian1@huawei.com Suggested-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> 
KASAN report following issue. The root cause is when opening 'hist'
file of an instance and accessing 'trace_event_file' in hist_show(),
but 'trace_event_file' has been freed due to the instance being removed.
'hist_debug' file has the same problem. To fix it, call
tracing_{open,release}_file_tr() in file_operations callback to have
the ref count and avoid 'trace_event_file' being freed.

  BUG: KASAN: slab-use-after-free in hist_show+0x11e0/0x1278
  Read of size 8 at addr ffff242541e336b8 by task head/190

  CPU: 4 PID: 190 Comm: head Not tainted 6.7.0-rc5-g26aff849438c #133
  Hardware name: linux,dummy-virt (DT)
  Call trace:
   dump_backtrace+0x98/0xf8
   show_stack+0x1c/0x30
   dump_stack_lvl+0x44/0x58
   print_report+0xf0/0x5a0
   kasan_report+0x80/0xc0
   __asan_report_load8_noabort+0x1c/0x28
   hist_show+0x11e0/0x1278
   seq_read_iter+0x344/0xd78
   seq_read+0x128/0x1c0
   vfs_read+0x198/0x6c8
   ksys_read+0xf4/0x1e0
   __arm64_sys_read+0x70/0xa8
   invoke_syscall+0x70/0x260
   el0_svc_common.constprop.0+0xb0/0x280
   do_el0_svc+0x44/0x60
   el0_svc+0x34/0x68
   el0t_64_sync_handler+0xb8/0xc0
   el0t_64_sync+0x168/0x170

  Allocated by task 188:
   kasan_save_stack+0x28/0x50
   kasan_set_track+0x28/0x38
   kasan_save_alloc_info+0x20/0x30
   __kasan_slab_alloc+0x6c/0x80
   kmem_cache_alloc+0x15c/0x4a8
   trace_create_new_event+0x84/0x348
   __trace_add_new_event+0x18/0x88
   event_trace_add_tracer+0xc4/0x1a0
   trace_array_create_dir+0x6c/0x100
   trace_array_create+0x2e8/0x568
   instance_mkdir+0x48/0x80
   tracefs_syscall_mkdir+0x90/0xe8
   vfs_mkdir+0x3c4/0x610
   do_mkdirat+0x144/0x200
   __arm64_sys_mkdirat+0x8c/0xc0
   invoke_syscall+0x70/0x260
   el0_svc_common.constprop.0+0xb0/0x280
   do_el0_svc+0x44/0x60
   el0_svc+0x34/0x68
   el0t_64_sync_handler+0xb8/0xc0
   el0t_64_sync+0x168/0x170

  Freed by task 191:
   kasan_save_stack+0x28/0x50
   kasan_set_track+0x28/0x38
   kasan_save_free_info+0x34/0x58
   __kasan_slab_free+0xe4/0x158
   kmem_cache_free+0x19c/0x508
   event_file_put+0xa0/0x120
   remove_event_file_dir+0x180/0x320
   event_trace_del_tracer+0xb0/0x180
   __remove_instance+0x224/0x508
   instance_rmdir+0x44/0x78
   tracefs_syscall_rmdir+0xbc/0x140
   vfs_rmdir+0x1cc/0x4c8
   do_rmdir+0x220/0x2b8
   __arm64_sys_unlinkat+0xc0/0x100
   invoke_syscall+0x70/0x260
   el0_svc_common.constprop.0+0xb0/0x280
   do_el0_svc+0x44/0x60
   el0_svc+0x34/0x68
   el0t_64_sync_handler+0xb8/0xc0
   el0t_64_sync+0x168/0x170

Link: https://lore.kernel.org/linux-trace-kernel/20231214012153.676155-1-zhengyejian1@huawei.com

Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
tracing/histograms: Simplify last_cmd_set() 2023-10-23T17:31:14+00:00 Christophe JAILLET christophe.jaillet@wanadoo.fr 2023-10-21T14:42:41+00:00 545db7e21e64766e6b7cb987fbfd3e79419726ce Turn a kzalloc()+strcpy()+strncat() into an equivalent and less verbose kasprintf(). Link: https://lore.kernel.org/linux-trace-kernel/30b6fb04dadc10a03cc1ad08f5d8a93ef623a167.1697899346.git.christophe.jaillet@wanadoo.fr Cc: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr> Reviewed-by: Mukesh ojha <quic_mojha@quicinc.com> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> 
Turn a kzalloc()+strcpy()+strncat() into an equivalent and less verbose
kasprintf().

Link: https://lore.kernel.org/linux-trace-kernel/30b6fb04dadc10a03cc1ad08f5d8a93ef623a167.1697899346.git.christophe.jaillet@wanadoo.fr

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Mukesh ojha <quic_mojha@quicinc.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
tracing/histograms: Return an error if we fail to add histogram to hist_vars list 2023-07-23T15:18:52+00:00 Mohamed Khalfella mkhalfella@purestorage.com 2023-07-14T20:33:41+00:00 4b8b3905165ef98386a3c06f196c85d21292d029 Commit 6018b585e8c6 ("tracing/histograms: Add histograms to hist_vars if they have referenced variables") added a check to fail histogram creation if save_hist_vars() failed to add histogram to hist_vars list. But the commit failed to set ret to failed return code before jumping to unregister histogram, fix it. Link: https://lore.kernel.org/linux-trace-kernel/20230714203341.51396-1-mkhalfella@purestorage.com Cc: stable@vger.kernel.org Fixes: 6018b585e8c6 ("tracing/histograms: Add histograms to hist_vars if they have referenced variables") Signed-off-by: Mohamed Khalfella <mkhalfella@purestorage.com> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> 
Commit 6018b585e8c6 ("tracing/histograms: Add histograms to hist_vars if
they have referenced variables") added a check to fail histogram creation
if save_hist_vars() failed to add histogram to hist_vars list. But the
commit failed to set ret to failed return code before jumping to
unregister histogram, fix it.

Link: https://lore.kernel.org/linux-trace-kernel/20230714203341.51396-1-mkhalfella@purestorage.com

Cc: stable@vger.kernel.org
Fixes: 6018b585e8c6 ("tracing/histograms: Add histograms to hist_vars if they have referenced variables")
Signed-off-by: Mohamed Khalfella <mkhalfella@purestorage.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
tracing/histograms: Add histograms to hist_vars if they have referenced variables 2023-07-12T23:08:56+00:00 Mohamed Khalfella mkhalfella@purestorage.com 2023-07-12T22:30:21+00:00 6018b585e8c6fa7d85d4b38d9ce49a5b67be7078 Hist triggers can have referenced variables without having direct variables fields. This can be the case if referenced variables are added for trigger actions. In this case the newly added references will not have field variables. Not taking such referenced variables into consideration can result in a bug where it would be possible to remove hist trigger with variables being refenced. This will result in a bug that is easily reproducable like so $ cd /sys/kernel/tracing $ echo 'synthetic_sys_enter char[] comm; long id' >> synthetic_events $ echo 'hist:keys=common_pid.execname,id.syscall:vals=hitcount:comm=common_pid.execname' >> events/raw_syscalls/sys_enter/trigger $ echo 'hist:keys=common_pid.execname,id.syscall:onmatch(raw_syscalls.sys_enter).synthetic_sys_enter($comm, id)' >> events/raw_syscalls/sys_enter/trigger $ echo '!hist:keys=common_pid.execname,id.syscall:vals=hitcount:comm=common_pid.execname' >> events/raw_syscalls/sys_enter/trigger [ 100.263533] ================================================================== [ 100.264634] BUG: KASAN: slab-use-after-free in resolve_var_refs+0xc7/0x180 [ 100.265520] Read of size 8 at addr ffff88810375d0f0 by task bash/439 [ 100.266320] [ 100.266533] CPU: 2 PID: 439 Comm: bash Not tainted 6.5.0-rc1 #4 [ 100.267277] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-20220807_005459-localhost 04/01/2014 [ 100.268561] Call Trace: [ 100.268902] <TASK> [ 100.269189] dump_stack_lvl+0x4c/0x70 [ 100.269680] print_report+0xc5/0x600 [ 100.270165] ? resolve_var_refs+0xc7/0x180 [ 100.270697] ? kasan_complete_mode_report_info+0x80/0x1f0 [ 100.271389] ? resolve_var_refs+0xc7/0x180 [ 100.271913] kasan_report+0xbd/0x100 [ 100.272380] ? resolve_var_refs+0xc7/0x180 [ 100.272920] __asan_load8+0x71/0xa0 [ 100.273377] resolve_var_refs+0xc7/0x180 [ 100.273888] event_hist_trigger+0x749/0x860 [ 100.274505] ? kasan_save_stack+0x2a/0x50 [ 100.275024] ? kasan_set_track+0x29/0x40 [ 100.275536] ? __pfx_event_hist_trigger+0x10/0x10 [ 100.276138] ? ksys_write+0xd1/0x170 [ 100.276607] ? do_syscall_64+0x3c/0x90 [ 100.277099] ? entry_SYSCALL_64_after_hwframe+0x6e/0xd8 [ 100.277771] ? destroy_hist_data+0x446/0x470 [ 100.278324] ? event_hist_trigger_parse+0xa6c/0x3860 [ 100.278962] ? __pfx_event_hist_trigger_parse+0x10/0x10 [ 100.279627] ? __kasan_check_write+0x18/0x20 [ 100.280177] ? mutex_unlock+0x85/0xd0 [ 100.280660] ? __pfx_mutex_unlock+0x10/0x10 [ 100.281200] ? kfree+0x7b/0x120 [ 100.281619] ? ____kasan_slab_free+0x15d/0x1d0 [ 100.282197] ? event_trigger_write+0xac/0x100 [ 100.282764] ? __kasan_slab_free+0x16/0x20 [ 100.283293] ? __kmem_cache_free+0x153/0x2f0 [ 100.283844] ? sched_mm_cid_remote_clear+0xb1/0x250 [ 100.284550] ? __pfx_sched_mm_cid_remote_clear+0x10/0x10 [ 100.285221] ? event_trigger_write+0xbc/0x100 [ 100.285781] ? __kasan_check_read+0x15/0x20 [ 100.286321] ? __bitmap_weight+0x66/0xa0 [ 100.286833] ? _find_next_bit+0x46/0xe0 [ 100.287334] ? task_mm_cid_work+0x37f/0x450 [ 100.287872] event_triggers_call+0x84/0x150 [ 100.288408] trace_event_buffer_commit+0x339/0x430 [ 100.289073] ? ring_buffer_event_data+0x3f/0x60 [ 100.292189] trace_event_raw_event_sys_enter+0x8b/0xe0 [ 100.295434] syscall_trace_enter.constprop.0+0x18f/0x1b0 [ 100.298653] syscall_enter_from_user_mode+0x32/0x40 [ 100.301808] do_syscall_64+0x1a/0x90 [ 100.304748] entry_SYSCALL_64_after_hwframe+0x6e/0xd8 [ 100.307775] RIP: 0033:0x7f686c75c1cb [ 100.310617] Code: 73 01 c3 48 8b 0d 65 3c 10 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa b8 21 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 35 3c 10 00 f7 d8 64 89 01 48 [ 100.317847] RSP: 002b:00007ffc60137a38 EFLAGS: 00000246 ORIG_RAX: 0000000000000021 [ 100.321200] RAX: ffffffffffffffda RBX: 000055f566469ea0 RCX: 00007f686c75c1cb [ 100.324631] RDX: 0000000000000001 RSI: 0000000000000001 RDI: 000000000000000a [ 100.328104] RBP: 00007ffc60137ac0 R08: 00007f686c818460 R09: 000000000000000a [ 100.331509] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000009 [ 100.334992] R13: 0000000000000007 R14: 000000000000000a R15: 0000000000000007 [ 100.338381] </TASK> We hit the bug because when second hist trigger has was created has_hist_vars() returned false because hist trigger did not have variables. As a result of that save_hist_vars() was not called to add the trigger to trace_array->hist_vars. Later on when we attempted to remove the first histogram find_any_var_ref() failed to detect it is being used because it did not find the second trigger in hist_vars list. With this change we wait until trigger actions are created so we can take into consideration if hist trigger has variable references. Also, now we check the return value of save_hist_vars() and fail trigger creation if save_hist_vars() fails. Link: https://lore.kernel.org/linux-trace-kernel/20230712223021.636335-1-mkhalfella@purestorage.com Cc: stable@vger.kernel.org Fixes: 067fe038e70f6 ("tracing: Add variable reference handling to hist triggers") Signed-off-by: Mohamed Khalfella <mkhalfella@purestorage.com> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> 
Hist triggers can have referenced variables without having direct
variables fields. This can be the case if referenced variables are added
for trigger actions. In this case the newly added references will not
have field variables. Not taking such referenced variables into
consideration can result in a bug where it would be possible to remove
hist trigger with variables being refenced. This will result in a bug
that is easily reproducable like so

$ cd /sys/kernel/tracing
$ echo 'synthetic_sys_enter char[] comm; long id' >> synthetic_events
$ echo 'hist:keys=common_pid.execname,id.syscall:vals=hitcount:comm=common_pid.execname' >> events/raw_syscalls/sys_enter/trigger
$ echo 'hist:keys=common_pid.execname,id.syscall:onmatch(raw_syscalls.sys_enter).synthetic_sys_enter($comm, id)' >> events/raw_syscalls/sys_enter/trigger
$ echo '!hist:keys=common_pid.execname,id.syscall:vals=hitcount:comm=common_pid.execname' >> events/raw_syscalls/sys_enter/trigger

[  100.263533] ==================================================================
[  100.264634] BUG: KASAN: slab-use-after-free in resolve_var_refs+0xc7/0x180
[  100.265520] Read of size 8 at addr ffff88810375d0f0 by task bash/439
[  100.266320]
[  100.266533] CPU: 2 PID: 439 Comm: bash Not tainted 6.5.0-rc1 #4
[  100.267277] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-20220807_005459-localhost 04/01/2014
[  100.268561] Call Trace:
[  100.268902]  <TASK>
[  100.269189]  dump_stack_lvl+0x4c/0x70
[  100.269680]  print_report+0xc5/0x600
[  100.270165]  ? resolve_var_refs+0xc7/0x180
[  100.270697]  ? kasan_complete_mode_report_info+0x80/0x1f0
[  100.271389]  ? resolve_var_refs+0xc7/0x180
[  100.271913]  kasan_report+0xbd/0x100
[  100.272380]  ? resolve_var_refs+0xc7/0x180
[  100.272920]  __asan_load8+0x71/0xa0
[  100.273377]  resolve_var_refs+0xc7/0x180
[  100.273888]  event_hist_trigger+0x749/0x860
[  100.274505]  ? kasan_save_stack+0x2a/0x50
[  100.275024]  ? kasan_set_track+0x29/0x40
[  100.275536]  ? __pfx_event_hist_trigger+0x10/0x10
[  100.276138]  ? ksys_write+0xd1/0x170
[  100.276607]  ? do_syscall_64+0x3c/0x90
[  100.277099]  ? entry_SYSCALL_64_after_hwframe+0x6e/0xd8
[  100.277771]  ? destroy_hist_data+0x446/0x470
[  100.278324]  ? event_hist_trigger_parse+0xa6c/0x3860
[  100.278962]  ? __pfx_event_hist_trigger_parse+0x10/0x10
[  100.279627]  ? __kasan_check_write+0x18/0x20
[  100.280177]  ? mutex_unlock+0x85/0xd0
[  100.280660]  ? __pfx_mutex_unlock+0x10/0x10
[  100.281200]  ? kfree+0x7b/0x120
[  100.281619]  ? ____kasan_slab_free+0x15d/0x1d0
[  100.282197]  ? event_trigger_write+0xac/0x100
[  100.282764]  ? __kasan_slab_free+0x16/0x20
[  100.283293]  ? __kmem_cache_free+0x153/0x2f0
[  100.283844]  ? sched_mm_cid_remote_clear+0xb1/0x250
[  100.284550]  ? __pfx_sched_mm_cid_remote_clear+0x10/0x10
[  100.285221]  ? event_trigger_write+0xbc/0x100
[  100.285781]  ? __kasan_check_read+0x15/0x20
[  100.286321]  ? __bitmap_weight+0x66/0xa0
[  100.286833]  ? _find_next_bit+0x46/0xe0
[  100.287334]  ? task_mm_cid_work+0x37f/0x450
[  100.287872]  event_triggers_call+0x84/0x150
[  100.288408]  trace_event_buffer_commit+0x339/0x430
[  100.289073]  ? ring_buffer_event_data+0x3f/0x60
[  100.292189]  trace_event_raw_event_sys_enter+0x8b/0xe0
[  100.295434]  syscall_trace_enter.constprop.0+0x18f/0x1b0
[  100.298653]  syscall_enter_from_user_mode+0x32/0x40
[  100.301808]  do_syscall_64+0x1a/0x90
[  100.304748]  entry_SYSCALL_64_after_hwframe+0x6e/0xd8
[  100.307775] RIP: 0033:0x7f686c75c1cb
[  100.310617] Code: 73 01 c3 48 8b 0d 65 3c 10 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa b8 21 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 35 3c 10 00 f7 d8 64 89 01 48
[  100.317847] RSP: 002b:00007ffc60137a38 EFLAGS: 00000246 ORIG_RAX: 0000000000000021
[  100.321200] RAX: ffffffffffffffda RBX: 000055f566469ea0 RCX: 00007f686c75c1cb
[  100.324631] RDX: 0000000000000001 RSI: 0000000000000001 RDI: 000000000000000a
[  100.328104] RBP: 00007ffc60137ac0 R08: 00007f686c818460 R09: 000000000000000a
[  100.331509] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000009
[  100.334992] R13: 0000000000000007 R14: 000000000000000a R15: 0000000000000007
[  100.338381]  </TASK>

We hit the bug because when second hist trigger has was created
has_hist_vars() returned false because hist trigger did not have
variables. As a result of that save_hist_vars() was not called to add
the trigger to trace_array->hist_vars. Later on when we attempted to
remove the first histogram find_any_var_ref() failed to detect it is
being used because it did not find the second trigger in hist_vars list.

With this change we wait until trigger actions are created so we can take
into consideration if hist trigger has variable references. Also, now we
check the return value of save_hist_vars() and fail trigger creation if
save_hist_vars() fails.

Link: https://lore.kernel.org/linux-trace-kernel/20230712223021.636335-1-mkhalfella@purestorage.com

Cc: stable@vger.kernel.org
Fixes: 067fe038e70f6 ("tracing: Add variable reference handling to hist triggers")
Signed-off-by: Mohamed Khalfella <mkhalfella@purestorage.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
tracing: Rename stacktrace field to common_stacktrace 2023-05-24T03:38:23+00:00 Steven Rostedt (Google) rostedt@goodmis.org 2023-05-24T03:09:13+00:00 4b512860bdbdddcf41467ebd394f27cb8dfb528c The histogram and synthetic events can use a pseudo event called "stacktrace" that will create a stacktrace at the time of the event and use it just like it was a normal field. We have other pseudo events such as "common_cpu" and "common_timestamp". To stay consistent with that, convert "stacktrace" to "common_stacktrace". As this was used in older kernels, to keep backward compatibility, this will act just like "common_cpu" did with "cpu". That is, "cpu" will be the same as "common_cpu" unless the event has a "cpu" field. In which case, the event's field is used. The same is true with "stacktrace". Also update the documentation to reflect this change. Link: https://lore.kernel.org/linux-trace-kernel/20230523230913.6860e28d@rorschach.local.home Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Tom Zanussi <zanussi@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> 
The histogram and synthetic events can use a pseudo event called
"stacktrace" that will create a stacktrace at the time of the event and
use it just like it was a normal field. We have other pseudo events such
as "common_cpu" and "common_timestamp". To stay consistent with that,
convert "stacktrace" to "common_stacktrace". As this was used in older
kernels, to keep backward compatibility, this will act just like
"common_cpu" did with "cpu". That is, "cpu" will be the same as
"common_cpu" unless the event has a "cpu" field. In which case, the
event's field is used. The same is true with "stacktrace".

Also update the documentation to reflect this change.

Link: https://lore.kernel.org/linux-trace-kernel/20230523230913.6860e28d@rorschach.local.home

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Tom Zanussi <zanussi@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>