io_uring: fix task_work add use-after-free with SQPOLL

Summary

In the Linux kernel, the following vulnerability has been resolved: io_uring: fix task_work add use-after-free with SQPOLL For SQPOLL, the sqpoll thread runs task_work off its own list and doesn't need to be told about it, so it can pop and complete a request as soon as mpscq_push() has published it. If that was the last request holding the ring alive, io_ring_exit_work() then frees the ctx, stops the thread, and with it the tctx, while io_req_normal_work_add() is still looking at both after the push: BUG: KASAN: slab-use-after-free in io_req_normal_work_add+0x439/0x510 Read of size 4 at addr ff11000000ca0000 by task repro/55 (...) BUG: KASAN: slab-use-after-free in queue_work_on+0x25/0x70 Write of size 8 at addr ff11000000c3bd00 by task repro/55 Hold an RCU read lock across the add, like io_req_local_work_add() already does, and have io_ring_exit_work() wait for a grace period for SQPOLL rings as well before freeing the ctx.

Timeline

1. Oct 18, 2026, 3:51 PM UTCCVE published
2. Oct 19, 2026, 9:26 AM UTCRecord last updated

Affected versions

• Linux Linux

  From af5d68f8892f8ee8f137648b79ceb2abc153a19b · fixed in 42b3332efacfd2140be4cd0dedad4fb96b8ae90e; From af5d68f8892f8ee8f137648b79ceb2abc153a19b · fixed in 891bd8335a0de3bb15c3b797ce3026bbb0dbef6c; From af5d68f8892f8ee8f137648b79ceb2abc153a19b · fixed in 395b25968fe854d4efaa19a8e9b7a5b6d1b3eea3; From af5d68f8892f8ee8f137648b79ceb2abc153a19b · fixed in a92193c91e8839fe5fc209616ea95465ae4b919d

• Linux Linux

  6.9

• KernelLinux

  From 6.9.0 · fixed in 6.12.113; From 6.13.0 · fixed in 6.18.56; From 6.19.0 · fixed in 7.2.10

References 4