From 0652fc95fb0fa0f35cd4abad26f5eabc0ecf64a3 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Thu, 11 Sep 2014 23:44:35 +0200 Subject: [PATCH] futex: Unlock hb->lock in futex_wait_requeue_pi() error path commit 13c42c2f43b19aab3195f2d357db00d1e885eaa8 upstream. futex_wait_requeue_pi() calls futex_wait_setup(). If futex_wait_setup() succeeds it returns with hb->lock held and preemption disabled. Now the sanity check after this does: if (match_futex(&q.key, &key2)) { ret = -EINVAL; goto out_put_keys; } which releases the keys but does not release hb->lock. So we happily return to user space with hb->lock held and therefor preemption disabled. Unlock hb->lock before taking the exit route. Reported-by: Dave "Trinity" Jones Signed-off-by: Thomas Gleixner Reviewed-by: Darren Hart Reviewed-by: Davidlohr Bueso Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1409112318500.4178@nanos Signed-off-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman --- kernel/futex.c | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/futex.c b/kernel/futex.c index e3087afb7429..0b0dc02aabce 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -2614,6 +2614,7 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags, * shared futexes. We need to compare the keys: */ if (match_futex(&q.key, &key2)) { + queue_unlock(hb); ret = -EINVAL; goto out_put_keys; } -- 2.39.5