Messages in this thread | | | Date | Wed, 18 Jul 2012 17:25:14 +0300 | From | Dan Carpenter <> | Subject | potential NULL dereference in futex_wait_requeue_pi() |
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Hi Darren,
The patch 52400ba94675: "futex: add requeue_pi functionality" from Apr 3, 2009, leads to the following warning: kernel/futex.c:2373 futex_wait_requeue_pi() error: potential NULL dereference 'pi_mutex'.
2330 if (!q.rt_waiter) { 2331 /* 2332 * Got the lock. We might not be the anticipated owner if we 2333 * did a lock-steal - fix up the PI-state in that case. 2334 */ 2335 if (q.pi_state && (q.pi_state->owner != current)) { 2336 spin_lock(q.lock_ptr); 2337 ret = fixup_pi_state_owner(uaddr2, &q, current);
pi_mutex is NULL here and it looks like fixup_pi_state_owner() can return -EFAULT.
2338 spin_unlock(q.lock_ptr); 2339 } 2340 } else {
[snipped]
2366 } 2367 2368 /* 2369 * If fixup_pi_state_owner() faulted and was unable to handle the 2370 * fault, unlock the rt_mutex and return the fault to userspace. 2371 */ 2372 if (ret == -EFAULT) { 2373 if (rt_mutex_owner(pi_mutex) == current) ^^^^^^^^ This will oops if pi_mutex is NULL.
2374 rt_mutex_unlock(pi_mutex); 2375 } else if (ret == -EINTR) {
regards, dan carpenter
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