tracing: Fix race where eprobes can be called before the event
authorSteven Rostedt (Google) <rostedt@goodmis.org>
Fri, 18 Nov 2022 02:42:49 +0000 (21:42 -0500)
committerMasami Hiramatsu (Google) <mhiramat@kernel.org>
Wed, 23 Nov 2022 15:42:18 +0000 (00:42 +0900)
commitd5f30a7da8ea8e6450250275cec5670cee3c4264
tree97a735066d689fe1ffddf904bdbc002482223012
parent40adaf51cb318131073d1ba8233d473cc105ecbf
tracing: Fix race where eprobes can be called before the event

The flag that tells the event to call its triggers after reading the event
is set for eprobes after the eprobe is enabled. This leads to a race where
the eprobe may be triggered at the beginning of the event where the record
information is NULL. The eprobe then dereferences the NULL record causing
a NULL kernel pointer bug.

Test for a NULL record to keep this from happening.

Link: https://lore.kernel.org/linux-trace-kernel/20221116192552.1066630-1-rafaelmendsr@gmail.com/
Link: https://lore.kernel.org/all/20221117214249.2addbe10@gandalf.local.home/
Cc: stable@vger.kernel.org
Fixes: 7491e2c442781 ("tracing: Add a probe that attaches to trace events")
Reported-by: Rafael Mendonca <rafaelmendsr@gmail.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
kernel/trace/trace_eprobe.c