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authorDarren Hart <dvhltc@us.ibm.com>2009-08-07 15:20:48 -0700
committerIngo Molnar <mingo@elte.hu>2009-08-10 20:38:11 +0200
commit392741e0a4e17c82e3978b7fcbf04291294dc0a1 (patch)
treec58437276d5eae05c46b3739d9bece01e357e6e2
parent4dc88029fd916b860ef063c40180aa604ce93494 (diff)
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 <dvhltc@us.ibm.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: John Kacur <jkacur@redhat.com> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Dinakar Guniguntala <dino@in.ibm.com> Cc: John Stultz <johnstul@linux.vnet.ibm.com> LKML-Reference: <4A7CA8C0.7010809@us.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
-rw-r--r--kernel/futex.c11
1 files 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