From: Pavel Begunkov <asml.silence@gmail.com> mainline inclusion from mainline-v5.13-rc2 commit 447c19f3b5074409c794b350b10306e1da1ef4ba category: bugfix bugzilla: 185736 CVE: NA ----------------------------------------------- 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: 90cd7e424969d ("io_uring: track link timeout's master explicitly") Reported-and-tested-by: syzbot+5a864149dd970b546223@syzkaller.appspotmail.com Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/69c46bf6ce37fec4fdcd98f0882e18eb07ce693a.162099012... Signed-off-by: Jens Axboe <axboe@kernel.dk> conflicts: fs/io_uring.c Signed-off-by: Ye Bin <yebin10@huawei.com> Reviewed-by: Zhang Yi <yi.zhang@huawei.com> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> --- 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 226e9f123f654..da61eeaf64e88 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -5925,8 +5925,8 @@ static enum hrtimer_restart io_link_timeout_fn(struct hrtimer *timer) if (!list_empty(&req->link_list)) { prev = list_entry(req->link_list.prev, struct io_kiocb, link_list); + list_del_init(&req->link_list); if (refcount_inc_not_zero(&prev->refs)) { - list_del_init(&req->link_list); prev->flags &= ~REQ_F_LINK_TIMEOUT; } else prev = NULL; -- 2.25.1