Commit-ID: 828b6f0e26170938d617e99a17177453be4d77a3
Gitweb: http://git.kernel.org/tip/828b6f0e26170938d617e99a17177453be4d77a3
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Wed, 27 Jan 2016 21:59:04 +0100
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Fri, 29 Jan 2016 08:35:24 +0100
perf: Fix NULL deref
Dan reported:
1229 if (ctx->task == TASK_TOMBSTONE ||
1230 !atomic_inc_not_zero(&ctx->refcount)) {
1231 raw_spin_unlock(&ctx->lock);
1232 ctx = NULL;
^^^^^^^^^^
ctx is NULL.
1233 }
1234
1235 WARN_ON_ONCE(ctx->task != task);
^^^^^^^^^^^^^^^^^
The patch adds a NULL dereference.
Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Stephane Eranian <eranian@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Vince Weaver <vincent.weaver@xxxxxxxxx>
Fixes: 63b6da39bb38 ("perf: Fix perf_event_exit_task() race")
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
kernel/events/core.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 1d243fa..fe97f95 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -1230,9 +1230,9 @@ retry:
!atomic_inc_not_zero(&ctx->refcount)) {
raw_spin_unlock(&ctx->lock);
ctx = NULL;
+ } else {
+ WARN_ON_ONCE(ctx->task != task);
}
-
- WARN_ON_ONCE(ctx->task != task);
}
rcu_read_unlock();
if (!ctx)
--
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