[PATCH 0/2] Two tracing patches for trace_events_hist.c

[PATCH 0/2] Two tracing patches for trace_events_hist.c

[Ammar Faizi]

Hi,

Two patches here.

## Patch 1
If `WARN_ON(!glob)` is ever triggered, we will still continue executing
the next lines. This will trigger the more serious problem, a NULL
pointer dereference bug. Just return -EINVAL if @glob is NULL.

## Patch 2
Change `if (strlen(glob))` to `if (glob[0])`. No need to traverse to
the end of string. If the first byte is not a NUL char, it's
guaranteed `if (strlen(glob))` is true.


Signed-off-by: Ammar Faizi <ammarfaizi2@gnuweeb.org>
---

Ammar Faizi (2):
  tracing: Return -EINVAL if WARN_ON(!glob) triggered in event_hist_trigger_parse()
  tracing: Change `if (strlen(glob))` to `if (glob[0])`

 kernel/trace/trace_events_hist.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)


base-commit: a1901b464e7e3e28956ae7423db2847dbbfb5be8
-- 
Ammar Faizi

[PATCH 1/2] tracing: Return -EINVAL if WARN_ON(!glob) triggered in event_hist_trigger_parse()

[Ammar Faizi]

If `WARN_ON(!glob)` is ever triggered, we will still continue executing
the next lines. This will trigger the more serious problem, a NULL
pointer dereference bug.

Just return -EINVAL if @glob is NULL.

Signed-off-by: Ammar Faizi <ammarfaizi2@gnuweeb.org>
---
 kernel/trace/trace_events_hist.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 44db5ba9cabb..0b99ad68e3fa 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -6186,7 +6186,8 @@ static int event_hist_trigger_parse(struct event_command *cmd_ops,
 
 	lockdep_assert_held(&event_mutex);
 
-	WARN_ON(!glob);
+	if (WARN_ON(!glob))
+		return -EINVAL;
 
 	if (strlen(glob)) {
 		hist_err_clear();
-- 
Ammar Faizi

[PATCH 2/2] tracing: Change `if (strlen(glob))` to `if (glob[0])`

[Ammar Faizi]

No need to traverse to the end of string. If the first byte is not a NUL
char, it's guaranteed `if (strlen(glob))` is true.

Signed-off-by: Ammar Faizi <ammarfaizi2@gnuweeb.org>
---
 kernel/trace/trace_events_hist.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 0b99ad68e3fa..1968e497ef44 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -6189,7 +6189,7 @@ static int event_hist_trigger_parse(struct event_command *cmd_ops,
 	if (WARN_ON(!glob))
 		return -EINVAL;
 
-	if (strlen(glob)) {
+	if (glob[0]) {
 		hist_err_clear();
 		last_cmd_set(file, param);
 	}
-- 
Ammar Faizi