Bug 2432358 (CVE-2025-71149)

Summary: CVE-2025-71149 kernel: io_uring/poll: correctly handle io_poll_add() return value on update
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Version: unspecifiedKeywords: Security
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OS: Linux   
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A logic flaw was found in the Linux kernel's io_uring poll handling. When using POLL_REMOVE to update events on a pending POLL_ADD request, if the update causes the poll to trigger, the completion queue entry (CQE) is lost and never posted to userspace. Additionally, successful completions are incorrectly overwritten with -ECANCELED, causing applications to receive wrong status codes.
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Description OSIDB Bzimport 2026-01-23 15:01:59 UTC 
In the Linux kernel, the following vulnerability has been resolved:

io_uring/poll: correctly handle io_poll_add() return value on update

When the core of io_uring was updated to handle completions
consistently and with fixed return codes, the POLL_REMOVE opcode
with updates got slightly broken. If a POLL_ADD is pending and
then POLL_REMOVE is used to update the events of that request, if that
update causes the POLL_ADD to now trigger, then that completion is lost
and a CQE is never posted.

Additionally, ensure that if an update does cause an existing POLL_ADD
to complete, that the completion value isn't always overwritten with
-ECANCELED. For that case, whatever io_poll_add() set the value to
should just be retained.
Comment 1 Keith Grant 2026-01-23 18:05:13 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026012328-CVE-2025-71149-c9ee@gregkh/T