perf/core: Fix potential NULL deref

Peter Zijlstra · Ingo Molnar · commit a71ef31485bb · 2023-10-24T12:15:12.000+02:00
Smatch is awesome. Fixes: 32671e3 ("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>
diff --git a/kernel/events/core.c b/kernel/events/core.c
@@ -13372,7 +13372,8 @@ static int inherit_group(struct perf_event *parent_event,
 		    !perf_get_aux_event(child_ctr, leader))
 			return -EINVAL;
 	}
-	leader->group_generation = parent_event->group_generation;
+	if (leader)
+		leader->group_generation = parent_event->group_generation;
 	return 0;
 }
 

Original file line number	Diff line number	Diff line change
`@@ -13372,7 +13372,8 @@ static int inherit_group(struct perf_event *parent_event,`
`13372`	`13372`	`!perf_get_aux_event(child_ctr, leader))`
`13373`	`13373`	`return -EINVAL;`
`13374`	`13374`	`}`
`13375`		`- leader->group_generation = parent_event->group_generation;`
	`13375`	`+ if (leader)`
	`13376`	`+ leader->group_generation = parent_event->group_generation;`
`13376`	`13377`	`return 0;`
`13377`	`13378`	`}`
`13378`	`13379`