From: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx> commit d5f30a7da8ea8e6450250275cec5670cee3c4264 upstream. 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@xxxxxxxxx/ Link: https://lore.kernel.org/all/20221117214249.2addbe10@xxxxxxxxxxxxxxxxxx/ Cc: stable@xxxxxxxxxxxxxxx Fixes: 7491e2c442781 ("tracing: Add a probe that attaches to trace events") Reported-by: Rafael Mendonca <rafaelmendsr@xxxxxxxxx> Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx> Acked-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx> Signed-off-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- kernel/trace/trace_eprobe.c | 3 +++ 1 file changed, 3 insertions(+) --- a/kernel/trace/trace_eprobe.c +++ b/kernel/trace/trace_eprobe.c @@ -567,6 +567,9 @@ static void eprobe_trigger_func(struct e if (unlikely(!rec)) return; + if (unlikely(!rec)) + return; + __eprobe_trace_func(edata, rec); }
