From: Pavel Begunkov <asml.silence@gmail.com> stable inclusion from stable-v6.6.68 commit 2ca94c8de36091067b9ce7527ae8db3812d38781 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IBEG43 CVE: CVE-2024-56709 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- commit dbd2ca9367eb19bc5e269b8c58b0b1514ada9156 upstream. task work can be executed after the task has gone through io_uring termination, whether it's the final task_work run or the fallback path. In this case, task work will find ->io_wq being already killed and null'ed, which is a problem if it then tries to forward the request to io_queue_iowq(). Make io_queue_iowq() fail requests in this case. Note that it also checks PF_KTHREAD, because the user can first close a DEFER_TASKRUN ring and shortly after kill the task, in which case ->iowq check would race. Cc: stable@vger.kernel.org Fixes: 50c52250e2d74 ("block: implement async io_uring discard cmd") Fixes: 773af69121ecc ("io_uring: always reissue from task_work context") Reported-by: Will <willsroot@protonmail.com> Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/63312b4a2c2bb67ad67b857d17a300e1d3b078e8.173463790... Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Yifan Qiao <qiaoyifan4@huawei.com> --- io_uring/io_uring.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index 69f5b73a609e..65dc2e344004 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -498,7 +498,11 @@ void io_queue_iowq(struct io_kiocb *req, struct io_tw_state *ts_dont_use) struct io_uring_task *tctx = req->task->io_uring; BUG_ON(!tctx); - BUG_ON(!tctx->io_wq); + + if ((current->flags & PF_KTHREAD) || !tctx->io_wq) { + io_req_task_queue_fail(req, -ECANCELED); + return; + } /* init ->work of the whole link before punting */ io_prep_async_link(req); -- 2.39.2