[PATCH 1/1] perf_event: add check for group_list if the parent isn't counted

Liming Wang
2009-12-30T11:55:22Z

If the parent has no entry in group_list, child_ctx will not be
allocated, which will lead dereference of a NULL child_ctx.

Signed-off-by: Liming Wang <liming.wang@windriver.com>
---
kernel/perf_event.c | 2 ++
1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 5b987b4..3664c4b 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -5126,6 +5126,8 @@ int perf_event_init_task(struct task_struct *child)
*/
mutex_lock(&parent_ctx->mutex);

+ if (list_empty(&parent_ctx->group_list))
+ goto exit;
/*
* We dont have to disable NMIs - we are only looking at
* the list, not manipulating it:
--
1.6.0.3