From ccb8c76757e3a3d20265965ab5d94ba66be2b116 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Wed, 9 Dec 2009 22:14:21 +0100
Subject: [PATCH] proc: Add missing rcu protection for __task_cred() in task_sig()

commit ccb8c76757e3a3d20265965ab5d94ba66be2b116 in tip.

task_sig() accesses __task_cred() without being in a RCU read side
critical section. tasklist_lock is not protecting that when
CONFIG_TREE_PREEMPT_RCU=y.

Add a rcu_read_lock/unlock() section around the code which accesses
__task_cred().

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: David Howells <dhowells@redhat.com>
Cc: James Morris <jmorris@namei.org>
Cc: linux-security-module@vger.kernel.org
Cc: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/proc/array.c b/fs/proc/array.c
index 91e2ae1..3dc9016 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -271,7 +271,9 @@ static inline void task_sig(struct seq_file *m, struct task_struct *p)
 		blocked = p->blocked;
 		collect_sigign_sigcatch(p, &ignored, &caught);
 		num_threads = atomic_read(&p->signal->count);
+		rcu_read_lock();
 		qsize = atomic_read(&__task_cred(p)->user->sigpending);
+		rcu_read_unlock();
 		qlim = p->signal->rlim[RLIMIT_SIGPENDING].rlim_cur;
 		unlock_task_sighand(p, &flags);
 	}
-- 
1.7.1.1