2.6.35-longterm review patch. If anyone has any objections, please let me know.
------------------ From: Manfred Spraul <manf...@colorfullife.com> [ upstream commit d694ad62bf539dbb20a0899ac2a954555f9e4a83 ] and IPC_RMID If a semaphore array is removed and in parallel a sleeping task is woken up (signal or timeout, does not matter), then the woken up task does not wait until wake_up_sem_queue_do() is completed. This will cause crashes, because wake_up_sem_queue_do() will read from a stale pointer. The fix is simple: Regardless of anything, always call get_queue_result(). This function waits until wake_up_sem_queue_do() has finished it's task. Addresses https://bugzilla.kernel.org/show_bug.cgi?id=27142 Reported-by: Yuriy Yevtukhov <yu...@ucoz.com> Reported-by: Harald Laabs <ker...@dasr.de> Signed-off-by: Manfred Spraul <manf...@colorfullife.com> Acked-by: Eric Dumazet <eric.duma...@gmail.com> Cc: <sta...@kernel.org> [2.6.35+] Signed-off-by: Andrew Morton <a...@linux-foundation.org> Signed-off-by: Linus Torvalds <torva...@linux-foundation.org> Signed-off-by: Andi Kleen <a...@linux.intel.com> Index: linux-2.6.35.y/ipc/sem.c =================================================================== --- linux-2.6.35.y.orig/ipc/sem.c +++ linux-2.6.35.y/ipc/sem.c @@ -1452,15 +1452,24 @@ SYSCALL_DEFINE4(semtimedop, int, semid, } sma = sem_lock(ns, semid); + + /* + * Wait until it's guaranteed that no wakeup_sem_queue_do() is ongoing. + */ + error = get_queue_result(&queue); + + /* + * Array removed? If yes, leave without sem_unlock(). + */ if (IS_ERR(sma)) { error = -EIDRM; goto out_free; } - error = get_queue_result(&queue); /* - * If queue.status != -EINTR we are woken up by another process + * If queue.status != -EINTR we are woken up by another process. + * Leave without unlink_queue(), but with sem_unlock(). */ if (error != -EINTR) { _______________________________________________ stable mailing list stable@linux.kernel.org http://linux.kernel.org/mailman/listinfo/stable
