From: Mandeep Singh Baines <msb@chromium.org>
Date: Thu, 8 Dec 2011 22:34:44 +0000 (-0800)
Subject: sys_getppid: add missing rcu_dereference
X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=031af165b1cd295ef04d2bfbcae9bc3cb9180735;p=deliverable%2Flinux.git

sys_getppid: add missing rcu_dereference

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@chromium.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/kernel/timer.c b/kernel/timer.c
index dbaa62422b13..9c3c62b0c4bc 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;