The patch titled
ipc/sem.c: fix race with concurrent semtimedop() timeouts and IPC_RMID
has been added to the -mm tree. Its filename is
ipc-semc-fix-race-with-concurrent-semtimedop-timeouts-and-ipc_rmid.patch
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------------------------------------------------------
Subject: ipc/sem.c: fix race with concurrent semtimedop() timeouts and IPC_RMID
From: Manfred Spraul <manf...@colorfullife.com>
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>
Cc: <sta...@kernel.org>
Signed-off-by: Andrew Morton <a...@linux-foundation.org>
---
ipc/sem.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
diff -puN
ipc/sem.c~ipc-semc-fix-race-with-concurrent-semtimedop-timeouts-and-ipc_rmid
ipc/sem.c
---
a/ipc/sem.c~ipc-semc-fix-race-with-concurrent-semtimedop-timeouts-and-ipc_rmid
+++ a/ipc/sem.c
@@ -1456,15 +1456,24 @@ 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) {
_
Patches currently in -mm which might be from manf...@colorfullife.com are
ipc-semc-fix-race-with-concurrent-semtimedop-timeouts-and-ipc_rmid.patch
ipc-mqueue-refactor-failure-handling.patch
ipc-mqueue-fix-mq_open-return-value.patch
slab-leaks3-default-y.patch
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