From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Brad Mouring" Subject: [PATCH] rtmutex.c: Fix incorrect waiter check Date: Fri, 5 Dec 2014 13:35:00 -0600 Message-ID: <1417808100-21626-1-git-send-email-brad.mouring@ni.com> Cc: "Paul McKenney" , linux-rt-users@vger.kernel.org, Brad Mouring To: "Thomas Gleixner" , "Steven Rostedt" Return-path: Received: from skprod2.natinst.com ([130.164.80.23]:34805 "EHLO ni.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751190AbaLEUST (ORCPT ); Fri, 5 Dec 2014 15:18:19 -0500 Sender: linux-rt-users-owner@vger.kernel.org List-ID: In task_blocks_on_lock, there's a null check on pi_blocked_on of the task_struct. This pointer can encode the fact that the task that contains the pointer is waking (preventing requeuing) and therefore is non-null. Use the inline function to avoid dereferencing an invalid "pointer" Signed-off-by: Brad Mouring Reported-by: Ben Shelton --- kernel/locking/rtmutex.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c index 6c40660..535321e 100644 --- a/kernel/locking/rtmutex.c +++ b/kernel/locking/rtmutex.c @@ -335,7 +335,8 @@ int max_lock_depth = 1024; static inline struct rt_mutex *task_blocked_on_lock(struct task_struct *p) { - return p->pi_blocked_on ? p->pi_blocked_on->lock : NULL; + return rt_mutex_real_waiter(p->pi_blocked_on) ? + p->pi_blocked_on->lock : NULL; } /* -- 1.8.3-rc3