From 392741e0a4e17c82e3978b7fcbf04291294dc0a1 Mon Sep 17 00:00:00 2001 From: Darren Hart Date: Fri, 7 Aug 2009 15:20:48 -0700 Subject: [PATCH] futex: Fix handling of bad requeue syscall pairing If futex_requeue(requeue_pi=1) finds a futex_q that was created by a call other the futex_wait_requeue_pi(), the q.rt_waiter may be null. If so, this will result in an oops from the following call graph: futex_requeue() rt_mutex_start_proxy_lock() task_blocks_on_rt_mutex() waiter->task dereference OOPS We currently WARN_ON() if this is detected, clearly this is inadequate. If we detect a mispairing in futex_requeue(), bail out, seding -EINVAL to user-space. V2: Fix parenthesis warnings. Signed-off-by: Darren Hart Acked-by: Peter Zijlstra Cc: Steven Rostedt Cc: John Kacur Cc: Eric Dumazet Cc: Dinakar Guniguntala Cc: John Stultz LKML-Reference: <4A7CA8C0.7010809@us.ibm.com> Signed-off-by: Ingo Molnar --- kernel/futex.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/kernel/futex.c b/kernel/futex.c index 8cc3ee1363a0..e18cfbdc7190 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -1256,8 +1256,15 @@ retry_private: if (!match_futex(&this->key, &key1)) continue; - WARN_ON(!requeue_pi && this->rt_waiter); - WARN_ON(requeue_pi && !this->rt_waiter); + /* + * FUTEX_WAIT_REQEUE_PI and FUTEX_CMP_REQUEUE_PI should always + * be paired with each other and no other futex ops. + */ + if ((requeue_pi && !this->rt_waiter) || + (!requeue_pi && this->rt_waiter)) { + ret = -EINVAL; + break; + } /* * Wake nr_wake waiters. For requeue_pi, if we acquired the -- 2.20.1