From: Pavel Begunkov asml.silence@gmail.com
[ Upstream commit 368c5481ae7c6a9719c40984faea35480d9f4872 ]
__io_kill_linked_timeout() sets REQ_F_COMP_LOCKED for a linked timeout even if it can't cancel it, e.g. it's already running. It not only races with io_link_timeout_fn() for ->flags field, but also leaves the flag set and so io_link_timeout_fn() may find it and decide that it holds the lock. Hopefully, the second problem is potential.
Signed-off-by: Pavel Begunkov asml.silence@gmail.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin sashal@kernel.org --- fs/io_uring.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c index 59ab8c5c2aaaa..50a7a99dad4ca 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -1650,6 +1650,7 @@ static bool io_link_cancel_timeout(struct io_kiocb *req)
ret = hrtimer_try_to_cancel(&req->io->timeout.timer); if (ret != -1) { + req->flags |= REQ_F_COMP_LOCKED; io_cqring_fill_event(req, -ECANCELED); io_commit_cqring(ctx); req->flags &= ~REQ_F_LINK_HEAD; @@ -1672,7 +1673,6 @@ static bool __io_kill_linked_timeout(struct io_kiocb *req) return false;
list_del_init(&link->link_list); - link->flags |= REQ_F_COMP_LOCKED; wake_ev = io_link_cancel_timeout(link); req->flags &= ~REQ_F_LINK_TIMEOUT; return wake_ev;