Bug 2565267 (CVE-2026-99230)

Summary:	CVE-2026-99230 kernel: kernel: Denial of Service via uninitialized list node in io_uring
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	A flaw was found in the Linux kernel's io_uring subsystem. When cancelable commands are removed, recycled request objects can retain stale list pointers instead of being cleanly reinitialized. A local attacker can trigger this issue by submitting specific asynchronous I/O requests, causing the kernel to dereference invalid memory. This flaw leads to a system crash, resulting in a Denial of Service (DoS).	Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-11-02 16:43:38 UTC

In the Linux kernel, the following vulnerability has been resolved:

io_uring/cmd: don't leave list poison in ->hash_node

io_uring_cmd_del_cancelable() uses hlist_del() to take a command off
->cancelable_uring_cmd, which leaves LIST_POISON1/2 behind in
->hash_node. Requests are recycled through the request cache without
being reinitialised, and not every user of ->hash_node sets it up before
it is used:

If a vectored futex wait is woken while futex_wait_multiple_setup() is
still queueing the futexes, io_futexv_wait() doesn't add the request to
->futex_list, and leaves the completion to the task_work queued by the
wake up. io_futexv_complete() ends in __io_futex_complete(), whose
hlist_del_init() is fine for a request that is unhashed, which is how all
other users of the node leave it. If the request was a cancelable
uring_cmd in its previous life, e.g. a ublk FETCH_REQ, it writes through
LIST_POISON2:

  Oops: general protection fault, probably for non-canonical address
  KASAN: maybe wild-memory-access in range [0xdead000000000120-...]
  RIP: 0010:io_futexv_complete+0x219/0x420
  Call Trace:
   tctx_task_work_run+0x804/0x950
   tctx_task_work+0x71/0xa0
   task_work_run+0x118/0x200

Leave the node unhashed.