Description
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.
Published: 2026-10-18
Score: n/a
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
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History

Sun, 18 Oct 2026 16:00:00 +0000

Type Values Removed Values Added
Description 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.
Title io_uring: fix task_work add use-after-free with SQPOLL
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

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Linux Linux Kernel
cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-10-18T15:51:19.578Z

Reserved: 2026-09-25T10:25:14.376Z

Link: CVE-2026-98858

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-10-18T16:17:40.257

Modified: 2026-10-18T16:17:40.257

Link: CVE-2026-98858

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses

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