linux-cve-announce - CVE-2025-40291: io_uring: fix regbuf vector size truncation

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Message-ID: <2025120815-CVE-2025-40291-8752@gregkh>
Date: Mon,  8 Dec 2025 09:47:16 +0900
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-40291: io_uring: fix regbuf vector size truncation

From: Greg Kroah-Hartman <gregkh@...nel.org>

Description
===========

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

io_uring: fix regbuf vector size truncation

There is a report of io_estimate_bvec_size() truncating the calculated
number of segments that leads to corruption issues. Check it doesn't
overflow "int"s used later. Rough but simple, can be improved on top.

The Linux kernel CVE team has assigned CVE-2025-40291 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 6.15 with commit 9ef4cbbcb4ac3786a1a4164507511b76b2a572c5 and fixed in 6.17.8 with commit 826ce37a842633efe1bb763e4b13045d74060d72
	Issue introduced in 6.15 with commit 9ef4cbbcb4ac3786a1a4164507511b76b2a572c5 and fixed in 6.18 with commit 146eb58629f45f8297e83d69e64d4eea4b28d972

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2025-40291
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	io_uring/rsrc.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/826ce37a842633efe1bb763e4b13045d74060d72
	https://git.kernel.org/stable/c/146eb58629f45f8297e83d69e64d4eea4b28d972