diff options
| author | Siddh Raman Pant <code@siddh.me> | 2023-06-05 20:06:16 +0530 |
|---|---|---|
| committer | Christian Brauner <brauner@kernel.org> | 2023-06-06 10:47:04 +0200 |
| commit | 943211c87427f25bd22e0e63849fb486bb5f87fa (patch) | |
| tree | c52147cc09a9a48ec908488f25575fed99c90ff2 /kernel | |
| parent | a7bc2e8ddf3c8e1f5bfeb401f7ee112956cea259 (diff) | |
watch_queue: prevent dangling pipe pointer
NULL the dangling pipe reference while clearing watch_queue.
If not done, a reference to a freed pipe remains in the watch_queue,
as this function is called before freeing a pipe in free_pipe_info()
(see line 834 of fs/pipe.c).
The sole use of wqueue->defunct is for checking if the watch queue has
been cleared, but wqueue->pipe is also NULLed while clearing.
Thus, wqueue->defunct is superfluous, as wqueue->pipe can be checked
for NULL. Hence, the former can be removed.
Tested with keyutils testsuite.
Cc: stable@vger.kernel.org # 6.1
Signed-off-by: Siddh Raman Pant <code@siddh.me>
Acked-by: David Howells <dhowells@redhat.com>
Message-Id: <20230605143616.640517-1-code@siddh.me>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/watch_queue.c | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/kernel/watch_queue.c b/kernel/watch_queue.c index e91cb4c2833f..d0b6b390ee42 100644 --- a/kernel/watch_queue.c +++ b/kernel/watch_queue.c @@ -42,7 +42,7 @@ MODULE_AUTHOR("Red Hat, Inc."); static inline bool lock_wqueue(struct watch_queue *wqueue) { spin_lock_bh(&wqueue->lock); - if (unlikely(wqueue->defunct)) { + if (unlikely(!wqueue->pipe)) { spin_unlock_bh(&wqueue->lock); return false; } @@ -104,9 +104,6 @@ static bool post_one_notification(struct watch_queue *wqueue, unsigned int head, tail, mask, note, offset, len; bool done = false; - if (!pipe) - return false; - spin_lock_irq(&pipe->rd_wait.lock); mask = pipe->ring_size - 1; @@ -603,8 +600,11 @@ void watch_queue_clear(struct watch_queue *wqueue) rcu_read_lock(); spin_lock_bh(&wqueue->lock); - /* Prevent new notifications from being stored. */ - wqueue->defunct = true; + /* + * This pipe can be freed by callers like free_pipe_info(). + * Removing this reference also prevents new notifications. + */ + wqueue->pipe = NULL; while (!hlist_empty(&wqueue->watches)) { watch = hlist_entry(wqueue->watches.first, struct watch, queue_node); |