CVE-2026-64425

Description

In the Linux kernel, the following vulnerability has been resolved: io_uring/io-wq: re-check IO_WQ_BIT_EXIT for each linked work item commit 10dc95939817 ("io_uring/io-wq: check IO_WQ_BIT_EXIT inside work run loop") fixed the obvious case where io_worker_handle_work() took one exit-bit snapshot before draining pending work, but the fix stops one level too early. io_worker_handle_work() now re-checks IO_WQ_BIT_EXIT in its outer work run loop, yet it still snapshots that bit once before processing a whole dependent linked-work chain. If io_wq_exit_start() sets IO_WQ_BIT_EXIT after the first linked item has started, the remaining linked items can still reuse stale do_kill = false, skip IO_WQ_WORK_CANCEL, and continue running after exit has begun. Move the check further inside, so it covers linked items too. Note: this is a syzbot special as it loves setting up tons of slow linked work on weird devices like msr that take forever to read, and immediately close the ring. Exit then takes a long time.

References

• https://git.kernel.org/stable/c/14b7ecad2ec56699325180a744f4b19f046401bb
• https://git.kernel.org/stable/c/1636d85dc139b07c0449308f2bb5e0c7a2e0da99
• https://git.kernel.org/stable/c/29bef9934b2521f787bb15dd1985d4c0d12ae02a
• https://git.kernel.org/stable/c/6e2f51f3e06773c2ee98ad09738f0908b48f76f9
• https://git.kernel.org/stable/c/ab85765cbe3258b43dc6729af0e6ce3a87a133d8