diff options
author | Darren Hart <dvhltc@us.ibm.com> | 2009-08-07 18:20:48 -0400 |
---|---|---|
committer | Ingo Molnar <mingo@elte.hu> | 2009-08-10 14:38:11 -0400 |
commit | 392741e0a4e17c82e3978b7fcbf04291294dc0a1 (patch) | |
tree | c58437276d5eae05c46b3739d9bece01e357e6e2 /kernel/futex.c | |
parent | 4dc88029fd916b860ef063c40180aa604ce93494 (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>
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 8cc3ee1363a..e18cfbdc719 100644 --- a/kernel/futex.c +++ b/kernel/futex.c | |||
@@ -1256,8 +1256,15 @@ retry_private: | |||
1256 | if (!match_futex(&this->key, &key1)) | 1256 | if (!match_futex(&this->key, &key1)) |
1257 | continue; | 1257 | continue; |
1258 | 1258 | ||
1259 | WARN_ON(!requeue_pi && this->rt_waiter); | 1259 | /* |
1260 | WARN_ON(requeue_pi && !this->rt_waiter); | 1260 | * FUTEX_WAIT_REQEUE_PI and FUTEX_CMP_REQUEUE_PI should always |
1261 | * be paired with each other and no other futex ops. | ||
1262 | */ | ||
1263 | if ((requeue_pi && !this->rt_waiter) || | ||
1264 | (!requeue_pi && this->rt_waiter)) { | ||
1265 | ret = -EINVAL; | ||
1266 | break; | ||
1267 | } | ||
1261 | 1268 | ||
1262 | /* | 1269 | /* |
1263 | * Wake nr_wake waiters. For requeue_pi, if we acquired the | 1270 | * Wake nr_wake waiters. For requeue_pi, if we acquired the |