From 54535b218454596e4892deaea713f39de83adb0a Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Google)" Date: Thu, 17 Nov 2022 21:42:49 -0500 Subject: [PATCH] tracing: Fix race where eprobes can be called before the event 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@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 Signed-off-by: Steven Rostedt (Google) Acked-by: Masami Hiramatsu (Google) Signed-off-by: Masami Hiramatsu (Google) Signed-off-by: Greg Kroah-Hartman --- kernel/trace/trace_eprobe.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/kernel/trace/trace_eprobe.c b/kernel/trace/trace_eprobe.c index 3b055aaee89a9..cae987f5a6524 100644 --- a/kernel/trace/trace_eprobe.c +++ b/kernel/trace/trace_eprobe.c @@ -560,6 +560,9 @@ static void eprobe_trigger_func(struct event_trigger_data *data, { struct eprobe_data *edata = data->private_data; + if (unlikely(!rec)) + return; + if (unlikely(!rec)) return; -- 2.47.2