kernel/linux.git/io_uring/poll.c, branch v6.1.175

io_uring/poll: fix multishot recv missing EOF on wakeup race

2026-06-01T15:38:50+00:00

[ Upstream commit a68ed2df72131447d131531a08fe4dfcf4fa4653 ] When a socket send and shutdown() happen back-to-back, both fire wake-ups before the receiver's task_work has a chance to run. The first wake gets poll ownership (poll_refs=1), and the second bumps it to 2. When io_poll_check_events() runs, it calls io_poll_issue() which does a recv that reads the data and returns IOU_RETRY. The loop then drains all accumulated refs (atomic_sub_return(2) -> 0) and exits, even though only the first event was consumed. Since the shutdown is a persistent state change, no further wakeups will happen, and the multishot recv can hang forever. Check specifically for HUP in the poll loop, and ensure that another loop is done to check for status if more than a single poll activation is pending. This ensures we don't lose the shutdown event. Backport notes for linux-6.1.y: - In 6.1.y the do-while masks v in the while-condition itself, so v can carry IO_POLL_RETRY_FLAG/IO_POLL_CANCEL_FLAG bits when we reach the multishot branch. The HUP check therefore compares `(v & IO_POLL_REF_MASK) != 1` rather than the upstream `v != 1`. - io_poll_issue takes `bool *locked` here (renamed to `ts` in 6.6+). - 6.1.y has no IOU_REQUEUE return path; only IOU_STOP_MULTISHOT. CVE: CVE-2026-23473 Cc: stable@vger.kernel.org # 6.1.y Fixes: dbc2564cfe0f ("io_uring: let fast poll support multishot") Reported-by: Francis Brosseau Link: https://github.com/axboe/liburing/issues/1549 Signed-off-by: Jens Axboe [backport for linux-6.1.y, verified 2026-05-01] Signed-off-by: Sasha Levin

io_uring/poll: ensure EPOLL_ONESHOT is propagated for EPOLL_URING_WAKE

2026-06-01T15:38:47+00:00

commit 1967f0b1cafdde37aa9e08e6021c14bcc484b7a5 upstream. Commit: aacf2f9f382c ("io_uring: fix req->apoll_events") fixed an issue where poll->events and req->apoll_events weren't synchronized, but then when the commit referenced in Fixes got added, it didn't ensure the same thing. If we mask in EPOLLONESHOT in the regular EPOLL_URING_WAKE path, then ensure it's done for both. Including a link to the original report below, even though it's mostly nonsense. But it includes a reproducer that does show that IORING_CQE_F_MORE is set in the previous CQE, while no more CQEs will be generated for this request. Just ignore anything that pretends this is security related in any way, it's just the typical AI nonsense. Cc: stable@vger.kernel.org Link: https://lore.kernel.org/io-uring/CAM0zi7yQzF3eKncgHo4iVM5yFLAjsiob_ucqyWKs=hyd_GqiMg@mail.gmail.com/ Reported-by: Azizcan Daştan Fixes: 4464853277d0 ("io_uring: pass in EPOLL_URING_WAKE for eventfd signaling and wakeups") Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

io_uring/poll: fix signed comparison in io_poll_get_ownership()

2026-06-01T15:38:47+00:00

commit 326941b22806cbf2df1fbfe902b7908b368cce42 upstream. io_poll_get_ownership() uses a signed comparison to check whether poll_refs has reached the threshold for the slowpath: if (unlikely(atomic_read(&req->poll_refs) >= IO_POLL_REF_BIAS)) atomic_read() returns int (signed). When IO_POLL_CANCEL_FLAG (BIT(31)) is set in poll_refs, the value becomes negative in signed arithmetic, so the >= 128 comparison always evaluates to false and the slowpath is never taken. Fix this by casting the atomic_read() result to unsigned int before the comparison, so that the cancel flag is treated as a large positive value and correctly triggers the slowpath. Fixes: a26a35e9019f ("io_uring: make poll refs more robust") Cc: stable@vger.kernel.org Reported-by: Yifan Wu Reported-by: Juefei Pu Co-developed-by: Yuan Tan Signed-off-by: Yuan Tan Suggested-by: Xin Liu Tested-by: Zhengchuan Liang Signed-off-by: Longxuan Yu Signed-off-by: Ren Wei Reviewed-by: Pavel Begunkov Link: https://patch.msgid.link/3a3508b08bcd7f1bc3beff848ae6e1d73d355043.1775965597.git.ylong030@ucr.edu Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

io_uring/cancel: support opcode based lookup and cancelation

2026-03-04T12:20:02+00:00

[ Upstream commit d7b8b079a8f6bc007d06d9ee468659dae6053e13 ] Add IORING_ASYNC_CANCEL_OP flag for cancelation, which allows the application to target cancelation based on the opcode of the original request. Signed-off-by: Jens Axboe Stable-dep-of: 22dbb0987bd1 ("io_uring/cancel: de-unionize file and user_data in struct io_cancel_data") Signed-off-by: Sasha Levin

io_uring/poll: correctly handle io_poll_add() return value on update

2026-01-11T14:18:56+00:00

Commit 84230ad2d2afbf0c44c32967e525c0ad92e26b4e upstream. When the core of io_uring was updated to handle completions consistently and with fixed return codes, the POLL_REMOVE opcode with updates got slightly broken. If a POLL_ADD is pending and then POLL_REMOVE is used to update the events of that request, if that update causes the POLL_ADD to now trigger, then that completion is lost and a CQE is never posted. Additionally, ensure that if an update does cause an existing POLL_ADD to complete, that the completion value isn't always overwritten with -ECANCELED. For that case, whatever io_poll_add() set the value to should just be retained. Cc: stable@vger.kernel.org Fixes: 97b388d70b53 ("io_uring: handle completions in the core") Reported-by: syzbot+641eec6b7af1f62f2b99@syzkaller.appspotmail.com Tested-by: syzbot+641eec6b7af1f62f2b99@syzkaller.appspotmail.com Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

io_uring: include dying ring in task_work "should cancel" state

2025-09-25T08:58:53+00:00

Commit 3539b1467e94336d5854ebf976d9627bfb65d6c3 upstream. When running task_work for an exiting task, rather than perform the issue retry attempt, the task_work is canceled. However, this isn't done for a ring that has been closed. This can lead to requests being successfully completed post the ring being closed, which is somewhat confusing and surprising to an application. Rather than just check the task exit state, also include the ring ref state in deciding whether or not to terminate a given request when run from task_work. Cc: stable@vger.kernel.org # 6.1+ Link: https://github.com/axboe/liburing/discussions/1459 Reported-by: Benedek Thaler Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

io_uring: backport io_should_terminate_tw()

2025-09-25T08:58:53+00:00

Parts of commit b6f58a3f4aa8dba424356c7a69388a81f4459300 upstream. Backport io_should_terminate_tw() helper to judge whether task_work should be run or terminated. Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

io_uring/poll: fix POLLERR handling

2025-07-24T06:51:48+00:00

commit c7cafd5b81cc07fb402e3068d134c21e60ea688c upstream. 8c8492ca64e7 ("io_uring/net: don't retry connect operation on EPOLLERR") is a little dirty hack that 1) wrongfully assumes that POLLERR equals to a failed request, which breaks all POLLERR users, e.g. all error queue recv interfaces. 2) deviates the connection request behaviour from connect(2), and 3) racy and solved at a wrong level. Nothing can be done with 2) now, and 3) is beyond the scope of the patch. At least solve 1) by moving the hack out of generic poll handling into io_connect(). Cc: stable@vger.kernel.org Fixes: 8c8492ca64e79 ("io_uring/net: don't retry connect operation on EPOLLERR") Signed-off-by: Pavel Begunkov Link: https://lore.kernel.org/r/3dc89036388d602ebd84c28e5042e457bdfc952b.1752682444.git.asml.silence@gmail.com Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

io_uring: fix multishots with selected buffers

2025-02-21T12:49:53+00:00

[ upstream commit d63b0e8a628e62ca85a0f7915230186bb92f8bb4 ] We do io_kbuf_recycle() when arming a poll but every iteration of a multishot can grab more buffers, which is why we need to flush the kbuf ring state before continuing with waiting. Cc: stable@vger.kernel.org Fixes: b3fdea6ecb55c ("io_uring: multishot recv") Reported-by: Muhammad Ramdhan Reported-by: Bing-Jhong Billy Jheng Reported-by: Jacob Soo Signed-off-by: Pavel Begunkov Link: https://lore.kernel.org/r/1bfc9990fe435f1fc6152ca9efeba5eb3e68339c.1738025570.git.asml.silence@gmail.com Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

io_uring/net: don't retry connect operation on EPOLLERR

2025-02-21T12:49:50+00:00

commit 8c8492ca64e79c6e0f433e8c9d2bcbd039ef83d0 upstream. If a socket is shutdown before the connection completes, POLLERR is set in the poll mask. However, connect ignores this as it doesn't know, and attempts the connection again. This may lead to a bogus -ETIMEDOUT result, where it should have noticed the POLLERR and just returned -ECONNRESET instead. Have the poll logic check for whether or not POLLERR is set in the mask, and if so, mark the request as failed. Then connect can appropriately fail the request rather than retry it. Reported-by: Sergey Galas Cc: stable@vger.kernel.org Link: https://github.com/axboe/liburing/discussions/1335 Fixes: 3fb1bd688172 ("io_uring/net: handle -EINPROGRESS correct for IORING_OP_CONNECT") Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman