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| author | Darren Hart <dvhltc@us.ibm.com> | 2009-08-07 15:20:48 -0700 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-08-10 20:38:11 +0200 |
| commit | 392741e0a4e17c82e3978b7fcbf04291294dc0a1 (patch) | |
| tree | c58437276d5eae05c46b3739d9bece01e357e6e2 /kernel/futex.c | |
| parent | 4dc88029fd916b860ef063c40180aa604ce93494 (diff) | |
| download | lwn-392741e0a4e17c82e3978b7fcbf04291294dc0a1.tar.gz lwn-392741e0a4e17c82e3978b7fcbf04291294dc0a1.zip | |
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>
Diffstat (limited to 'kernel/futex.c')
| -rw-r--r-- | kernel/futex.c | 11 |
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 |