CVE-2026-99268
UnknownSummary
In io_uring with IORING_SETUP_DEFER_TASKRUN, completions are queued as local work and only become CQEs when the submitter enters the kernel to wait for events. io_uring_poll() reports EPOLLIN if local work is pending, but only if the work exists at call time; after DEFER_TASKRUN was added, the ->poll_wq wakeup was replaced by directly waking the submitter, so poll() can sleep despite pending work. The fix wakes ->poll_wq when the first entry is put on the work list, using an RCU callback when needed.
Risk Assessment
Applications using io_uring with DEFER_TASKRUN may hang in poll()/epoll waiting for completions that never wake the thread. This can cause application delays or hangs.
Recommendation
Update the Linux kernel to a version with the fix. Test applications using io_uring and DEFER_TASKRUN for correct poll() wakeups.
Other vulnerabilities in Linux kernel
See all- CVE-2026-99269Unknown
In the Linux kernel sched_ext scheduler, a task can be found on a non-local DSQ while the CPU that dispatched it is still running ops.dequeue() and hasn't cleared SCX_OPSS_DISPATCHING. The DSQ consume and move paths don't wait for dispatch to finish and can operate on the task concurrently with the dispatcher. The fix adds scx_wait_dispatching() before operating on the task.
- CVE-2026-99267Unknown
In io_uring NAPI with dynamic tracking, a NAPI id not seen for a minute should be dropped from the ring's busy-poll list. However, the timeout is computed incorrectly — SEC_CONVERSION is used instead of the number of jiffies per second, giving about eight years for HZ=1000 and overflowing on 32-bit systems. As a result, entries are never removed and every wait polls all historical ids.
- CVE-2026-99266Unknown
In io_uring zcrx, io_zcrx_queue_cqe() computes the buffer offset in its area from net_iov_idx(), which is an unsigned int, so the shift is done in 32 bits and only the result is widened to the u64 placed in the CQE. An area can be up to 1 TB, so for every niov beyond the first 4 GB the CQE points the application at a buffer 4 GB (or a multiple) below the correct one. The application reads wrong data and returns a buffer it doesn't own via the refill queue while the real one is never given back.
- CVE-2026-99265Unknown
In io_uring/openclose, io_pipe_fixed() installs both ends of the pipe in the fixed file table, drops ->uring_lock, and copies the slot numbers to the application. If that faults, it takes the lock again and removes whatever is in these slots. If the request is run by io-wq, the lock really is dropped and the slots are visible to others; by the time the error path gets to them, they may have been closed and reused (by IORING_OP_CLOSE, direct open/accept, or IORING_REGISTER_FILES_UPDATE), causing removal of a file unrelated to the failed request. The fix performs the copy with the lock held.
- CVE-2026-99264Unknown
A bug was fixed in the Linux kernel's io_uring/net handling of recv retries on uncommitted buffers. When a receive was retried after a partial transfer, the kernel could hand out buffer memory that the retried request was still writing to, causing data overwrites. The request is now completed with the bytes received instead of retried, and MSG_WAITALL is no longer honoured for incremental buffers or multi-buffer bundles.
- CVE-2026-99263Unknown
In io_uring/poll, if a wakeup sets IO_POLL_RETRY_FLAG between the owning task consuming the existing instance of IO_POLL_RETRY_FLAG and the loop check in io_poll_check_events(), request processing stalls until an unrelated wakeup arrives. The fix uses atomic_cmpxchg instead of atomic_sub_return to guarantee both the count v and poll_refs are 0 and no wakeups are missed.
- CVE-2026-99262Unknown
In io_uring/timeout, an IORING_OP_TIMEOUT run by io-wq due to IOSQE_ASYNC has the same problem as poll, futex, and waitid. io_wq_submit_work() checks IO_WQ_WORK_CANCEL only once before issuing the request; a cancel in between flags the work, gets -EALREADY, and searches ->timeout_list in vain while the worker adds the request and starts the timer. Nobody checks the flag again and the timeout runs its course, and at ring exit a task can get stuck for the full duration. The fix checks the flag under ->timeout_lock and fails the request if set.
- CVE-2026-99261Unknown
In the drm/amdgpu driver, reservation fence slot allocation for eviction of userq per-vm BOs has been corrected. The fix addresses both the move overflow and the eviction fence add for these buffers.
- CVE-2026-99260Unknown
In the NTFS filesystem, ntfs_new_attr_flags skipped the resident-to-non-resident conversion when setting sparse/compressed flags on a resident attribute and terminated. The fix corrects this conversion.
- CVE-2026-99259Unknown
In the Linux kernel, the soc/tegra: pmc driver has an uninitialised early_pmc->rate variable for legacy 32-bit Tegra devices. The variable is never configured and remains 0, triggering a warning in tegra_pmc_enter_suspend_mode(). The issue appeared after the PMC driver was changed to create the PMC context dynamically, updating rate only in the new context.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: io_uring: wake ring pollers for local task_work With IORING_SETUP_DEFER_TASKRUN completions are queued as local work, and only become CQEs when the submitter enters the kernel to wait for events. For an application that finds out via poll() or epoll on the ring fd when it is time to do that, io_uring_poll() reports EPOLLIN if local work is pending. That only helps if the work is there at the time of the call. When DEFER_TASKRUN was added, io_req_local_work_add() did io_cqring_wake(), which took care of tasks sleeping in poll() as well. Then polling got a wait queue of its own, ->poll_wq, and the wake up in io_req_local_work_add() was replaced by waking the submitter directly. Since then ->poll_wq is only woken when CQEs are committed, which for such a ring is done by the very task that is waiting to be told to: submitter completion poll(ring_fd) io_uring_poll() // nothing yet schedule() io_req_local_work_add() // ->cq_wait_nr: nobody waits // sleeps on Wake ->poll_wq when the first entry is put on the work list. Like for the eventfd, that must not be done right away if the work is queued from a wake up handler, as the chain of wake ups could get back to the wait queue whose lock is held. Use an RCU callback in that case, with a reference to the ring.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS