[PATCH] sys_getppid: add missing rcu_dereference

[Mandeep Singh Baines]

In order to safely dereference current->real_parent inside an
rcu_read_lock, we need an rcu_dereference.

Signed-off-by: Mandeep Singh Baines <msb@xxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Pavel Emelyanov <xemul@xxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Kees Cook <kees@xxxxxxxxxxxx>
---
 kernel/timer.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/kernel/timer.c b/kernel/timer.c
index dbaa624..9c3c62b 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -1368,7 +1368,7 @@ SYSCALL_DEFINE0(getppid)
 	int pid;
 
 	rcu_read_lock();
-	pid = task_tgid_vnr(current->real_parent);
+	pid = task_tgid_vnr(rcu_dereference(current->real_parent));
 	rcu_read_unlock();
 
 	return pid;
-- 
1.7.3.1

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