perf: Fix task_struct reference leak

sys_perf_event_open() had an imbalance in the number of task refs it
took causing memory leakage

Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: stable@kernel.org # .37+
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 5 insertions, 0 deletions

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 261690923ffb..27960f114efd 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -6531,6 +6531,11 @@ SYSCALL_DEFINE5(perf_event_open,
                 goto err_alloc;
         }
 
+        if (task) {
+                put_task_struct(task);
+                task = NULL;
+        }
+
         /*
          * Look up the group leader (we will attach this event to it):
          */