diff options
| -rw-r--r-- | kernel/futex.c | 21 |
1 files changed, 19 insertions, 2 deletions
diff --git a/kernel/futex.c b/kernel/futex.c index 06e8240d2abe..e7a35f1039e7 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -530,8 +530,25 @@ lookup_pi_state(u32 uval, struct futex_hash_bucket *hb, return -EINVAL; WARN_ON(!atomic_read(&pi_state->refcount)); - WARN_ON(pid && pi_state->owner && - pi_state->owner->pid != pid); + + /* + * When pi_state->owner is NULL then the owner died + * and another waiter is on the fly. pi_state->owner + * is fixed up by the task which acquires + * pi_state->rt_mutex. + * + * We do not check for pid == 0 which can happen when + * the owner died and robust_list_exit() cleared the + * TID. + */ + if (pid && pi_state->owner) { + /* + * Bail out if user space manipulated the + * futex value. + */ + if (pid != task_pid_vnr(pi_state->owner)) + return -EINVAL; + } atomic_inc(&pi_state->refcount); *ps = pi_state; |