io-wq: check that the predecessor is hashed in io_wq_remove_pending()

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Summary

CVECVE-2026-46274
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-06-08 16:16:40 UTC
Updated2026-06-08 16:16:40 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: io-wq: check that the predecessor is hashed in io_wq_remove_pending() io_wq_remove_pending() needs to fix up wq->hash_tail[] if the cancelled work was the tail of its hash bucket. When doing this, it checks whether the preceding entry in acct->work_list has the same hash value, but never checks that the predecessor is hashed at all. io_get_work_hash() is simply atomic_read(&work->flags) >> IO_WQ_HASH_SHIFT, and the hash bits are never set for non-hashed work, so it returns 0. Thus, when a hashed bucket-0 work is cancelled while a non-hashed work is its list predecessor, the check spuriously passes and a pointer to the non-hashed io_kiocb is stored in wq->hash_tail[0]. Because non-hashed work is dequeued via the fast path in io_get_next_work(), which never touches hash_tail[], the stale pointer is never cleared. Therefore, after the non-hashed io_kiocb completes and is freed back to req_cachep, wq->hash_tail[0] is a dangling pointer. The io_wq is per-task (tctx->io_wq) and survives ring open/close, so the dangling pointer persists for the lifetime of the task; the next hashed bucket-0 enqueue dereferences it in io_wq_insert_work() and wq_list_add_after() writes through freed memory. Add the missing io_wq_is_hashed() check so a non-hashed predecessor never inherits a hash_tail[] slot.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 204361a77f4018627addd4a06877448f088ddfc0 d6bda9df0c0a3080804181464d5c0f4d78a4e769 git Not specified
CNA Linux Linux affected 204361a77f4018627addd4a06877448f088ddfc0 5a20ebf0c81b61f5ea3b1b529c100cad69b9f603 git Not specified
CNA Linux Linux affected 204361a77f4018627addd4a06877448f088ddfc0 252c5051dba9c709b6a72f2866f93e5e618b3f06 git Not specified
CNA Linux Linux affected 204361a77f4018627addd4a06877448f088ddfc0 d376c131af7c7739a87ff037ed2fdb67c2542c8a git Not specified
CNA Linux Linux affected 204361a77f4018627addd4a06877448f088ddfc0 d6a2d7b04b5a093021a7a0e2e69e9d5237dfa8cc git Not specified
CNA Linux Linux affected 13f35a2c0fd5c6a4fcd8903542b053bcc914fcf5 git Not specified
CNA Linux Linux affected 5.8.6 5.9 semver Not specified
CNA Linux Linux affected 5.9 Not specified
CNA Linux Linux unaffected 5.9 semver Not specified
CNA Linux Linux unaffected 6.6.141 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.91 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.33 6.18.* semver Not specified
CNA Linux Linux unaffected 7.0.10 7.0.* semver Not specified
CNA Linux Linux unaffected 7.1-rc4 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/5a20ebf0c81b61f5ea3b1b529c100cad69b9f603 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/d376c131af7c7739a87ff037ed2fdb67c2542c8a 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/d6bda9df0c0a3080804181464d5c0f4d78a4e769 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/252c5051dba9c709b6a72f2866f93e5e618b3f06 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/d6a2d7b04b5a093021a7a0e2e69e9d5237dfa8cc 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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