linux-cve-announce - CVE-2025-39822: io_uring/kbuf: fix signedness in this

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Message-ID: <2025091616-CVE-2025-39822-454e@gregkh>
Date: Tue, 16 Sep 2025 15:00:28 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-39822: io_uring/kbuf: fix signedness in this_len calculation

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

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

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

io_uring/kbuf: fix signedness in this_len calculation

When importing and using buffers, buf->len is considered unsigned.
However, buf->len is converted to signed int when committing. This can
lead to unexpected behavior if the buffer is large enough to be
interpreted as a negative value. Make min_t calculation unsigned.

The Linux kernel CVE team has assigned CVE-2025-39822 to this issue.


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

	Issue introduced in 6.12 with commit ae98dbf43d755b4e111fcd086e53939bef3e9a1a and fixed in 6.16.5 with commit f4f411c068402c370c4f9a9d4950a97af97bbbb1
	Issue introduced in 6.12 with commit ae98dbf43d755b4e111fcd086e53939bef3e9a1a and fixed in 6.17-rc4 with commit c64eff368ac676e8540344d27a3de47e0ad90d21

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-2025-39822
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/kbuf.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/f4f411c068402c370c4f9a9d4950a97af97bbbb1
	https://git.kernel.org/stable/c/c64eff368ac676e8540344d27a3de47e0ad90d21