Commit 447c19f3 authored by Pavel Begunkov's avatar Pavel Begunkov Committed by Jens Axboe

io_uring: fix ltout double free on completion race

Always remove linked timeout on io_link_timeout_fn() from the master
request link list, otherwise we may get use-after-free when first
io_link_timeout_fn() puts linked timeout in the fail path, and then
will be found and put on master's free.

Cc: stable@vger.kernel.org # 5.10+
Fixes: 90cd7e42 ("io_uring: track link timeout's master explicitly")
Reported-and-tested-by: syzbot+5a864149dd970b546223@syzkaller.appspotmail.com
Signed-off-by: default avatarPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/69c46bf6ce37fec4fdcd98f0882e18eb07ce693a.1620990121.git.asml.silence@gmail.comSigned-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent a298232e
...@@ -6354,10 +6354,11 @@ static enum hrtimer_restart io_link_timeout_fn(struct hrtimer *timer) ...@@ -6354,10 +6354,11 @@ static enum hrtimer_restart io_link_timeout_fn(struct hrtimer *timer)
* We don't expect the list to be empty, that will only happen if we * We don't expect the list to be empty, that will only happen if we
* race with the completion of the linked work. * race with the completion of the linked work.
*/ */
if (prev && req_ref_inc_not_zero(prev)) if (prev) {
io_remove_next_linked(prev); io_remove_next_linked(prev);
else if (!req_ref_inc_not_zero(prev))
prev = NULL; prev = NULL;
}
spin_unlock_irqrestore(&ctx->completion_lock, flags); spin_unlock_irqrestore(&ctx->completion_lock, flags);
if (prev) { if (prev) {
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment