Merge tag 'trace-v7.2-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull tracing fixes from Steven Rostedt:

 - Reset dropped_count in mmio_reset_data()

   When mmio_reset_data() is called, it does not reset the dropped_count
   so that subsequent runs will have incorrect reporting.

 - Add NULL check for mmio_trace_array in logging functions

   The functions __trace_mmiotrace_rw() and __trace_mmiotrace_map() may
   have the 'tr' variable passed to it as NULL. But they both
   dereference it without checking if it is NULL first.

 - Check return value of __register_event() in trace_module_add_events()

   If __register_event() fails, the __add_event_to_tracers() call after
   it will create a file for it. If the module fails to load and its
   memory is freed, the file will still point to it and it will not be
   removed as the registering of the event did not complete.

   Only call __add_event_to_tracers() if the __register_event() was
   successful.

 - Fix false positive match in regex_match_full()

   The regex full matching uses a strncmp() to test against the match
   string and the value. It should not match if value is a prefix of the
   string to match. Check to make sure the length of the strings match
   before comparing.

 - Fix reader page read offset for remote buffers

   A page swapped in by __rb_get_reader_page_from_remote() retains its
   stale read offset, causing subsequent reads to skip events or read
   past valid data.

 - Fix memory leak of subbuf_ids in rb_allocate_cpu_buffer()

   Remote buffers allocate a subbuf_ids array. If the allocator function
   fails after it is allocated, it does not free it, resulting in a
   memory leak.

* tag 'trace-v7.2-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Fix subbuf_ids memory leak in rb_allocate_cpu_buffer() error path
  ring-buffer: Fix reader page read offset for remote buffers
  tracing/filters: Fix false positive match in regex_match_full()
  tracing: Check return value of __register_event() in trace_module_add_events()
  tracing/mmiotrace: Add NULL check for mmio_trace_array in logging functions
  tracing/mmiotrace: Reset dropped_count in mmio_reset_data()

4 files changed, 18 insertions, 4 deletions

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 804ccae694d2..8e2485bb3aa8 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -2599,6 +2599,7 @@ rb_allocate_cpu_buffer(struct trace_buffer *buffer, long nr_pages, int cpu)
 	return_ptr(cpu_buffer);
 
  fail_free_reader:
+	kfree(cpu_buffer->subbuf_ids);
 	free_buffer_page(cpu_buffer->reader_page);
 
 	return NULL;
@@ -5783,6 +5784,7 @@ __rb_get_reader_page_from_remote(struct ring_buffer_per_cpu *cpu_buffer)
 
 	cpu_buffer->head_page = new_head;
 	cpu_buffer->reader_page = new_reader;
+	cpu_buffer->reader_page->read = 0;
 	cpu_buffer->pages = &new_head->list;
 	cpu_buffer->read_stamp = new_reader->page->time_stamp;
 	cpu_buffer->lost_events = cpu_buffer->meta_page->reader.lost_events;
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 956692856fa8..c01b10b99f67 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -3933,8 +3933,8 @@ static void trace_module_add_events(struct module *mod)
 	end = mod->trace_events + mod->num_trace_events;
 
 	for_each_event(call, start, end) {
-		__register_event(*call, mod);
-		__add_event_to_tracers(*call);
+		if (!__register_event(*call, mod))
+			__add_event_to_tracers(*call);
 	}
 
 	update_cache_events(mod);
diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index 6385cd662d8d..2b46ca536045 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -1027,6 +1027,9 @@ static int regex_match_full(char *str, struct regex *r, int len)
 	if (!len)
 		return strcmp(str, r->pattern) == 0;
 
+	if (len < r->len)
+		return 0;
+
 	return strncmp(str, r->pattern, len) == 0;
 }
 
diff --git a/kernel/trace/trace_mmiotrace.c b/kernel/trace/trace_mmiotrace.c
index b88b8d9923ad..df8692c2dea8 100644
--- a/kernel/trace/trace_mmiotrace.c
+++ b/kernel/trace/trace_mmiotrace.c
@@ -29,6 +29,7 @@ static void mmio_reset_data(struct trace_array *tr)
 {
 	overrun_detected = false;
 	prev_overruns = 0;
+	atomic_set(&dropped_count, 0);
 
 	tracing_reset_online_cpus(&tr->array_buffer);
 }
@@ -293,11 +294,15 @@ device_initcall(init_mmio_trace);
 static void __trace_mmiotrace_rw(struct trace_array *tr,
 				struct mmiotrace_rw *rw)
 {
-	struct trace_buffer *buffer = tr->array_buffer.buffer;
+	struct trace_buffer *buffer;
 	struct ring_buffer_event *event;
 	struct trace_mmiotrace_rw *entry;
 	unsigned int trace_ctx;
 
+	if (!tr)
+		return;
+
+	buffer = tr->array_buffer.buffer;
 	trace_ctx = tracing_gen_ctx_flags(0);
 	event = trace_buffer_lock_reserve(buffer, TRACE_MMIO_RW,
 					  sizeof(*entry), trace_ctx);
@@ -320,11 +325,15 @@ void mmio_trace_rw(struct mmiotrace_rw *rw)
 static void __trace_mmiotrace_map(struct trace_array *tr,
 				struct mmiotrace_map *map)
 {
-	struct trace_buffer *buffer = tr->array_buffer.buffer;
+	struct trace_buffer *buffer;
 	struct ring_buffer_event *event;
 	struct trace_mmiotrace_map *entry;
 	unsigned int trace_ctx;
 
+	if (!tr)
+		return;
+
+	buffer = tr->array_buffer.buffer;
 	trace_ctx = tracing_gen_ctx_flags(0);
 	event = trace_buffer_lock_reserve(buffer, TRACE_MMIO_MAP,
 					  sizeof(*entry), trace_ctx);