perf: Fix task_struct reference leak

BugLink: http://bugs.launchpad.net/bugs/761134

commit fd1edb3aa2c1d92618d8f0c6d15d44ea41fcac6a upstream.

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>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index f81f9d6..07fcc85 100644 (file)
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -5917,6 +5917,11 @@ 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):
         */