From: Peter Zijlstra <peterz@infradead.org>
Date: Tue, 24 Oct 2023 11:42:21 +0200
Subject: perf/core: Fix potential NULL deref
Git-commit: a71ef31485bb51b846e8db8b3a35e432cc15afb5
Patch-mainline: v6.6
References: bsc#1216584 CVE-2023-5717
X-Info: adjust for context (core.c) no aux_output fix (f733c6b508bcaa3441ba1eacf16efb9abd47489f)

Smatch is awesome.

Fixes: 32671e3799ca ("perf: Disallow mis-matched inherited group reads")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Tony Jones <tonyj@suse.de>
---
 kernel/events/core.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index d0663b9324e7..a2f2a9525d72 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -13372,7 +13372,8 @@ static int inherit_group(struct perf_event *parent_event,
 		if (IS_ERR(child_ctr))
 			return PTR_ERR(child_ctr);
 	}
-	leader->group_generation = parent_event->group_generation;
+	if (leader)
+		leader->group_generation = parent_event->group_generation;
 	return 0;
 }