linux-cve-announce - CVE-2025-21837: io_uring/uring_cmd: unconditionally copy SQEs at prep time

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Message-ID: <2025030706-CVE-2025-21837-85ef@gregkh>
Date: Fri,  7 Mar 2025 10:10:07 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2025-21837: io_uring/uring_cmd: unconditionally copy SQEs at prep time

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

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

io_uring/uring_cmd: unconditionally copy SQEs at prep time

This isn't generally necessary, but conditions have been observed where
SQE data is accessed from the original SQE after prep has been done and
outside of the initial issue. Opcode prep handlers must ensure that any
SQE related data is stable beyond the prep phase, but uring_cmd is a bit
special in how it handles the SQE which makes it susceptible to reading
stale data. If the application has reused the SQE before the original
completes, then that can lead to data corruption.

Down the line we can relax this again once uring_cmd has been sanitized
a bit, and avoid unnecessarily copying the SQE.

The Linux kernel CVE team has assigned CVE-2025-21837 to this issue.

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

	Issue introduced in 6.10 with commit 5eff57fa9f3aae3acbcaf196af507eec58955f3b and fixed in 6.13.4 with commit 87fe1d68842a308998b315c8ed0163a1d639017c
	Issue introduced in 6.10 with commit 5eff57fa9f3aae3acbcaf196af507eec58955f3b and fixed in 6.14-rc3 with commit d6211ebbdaa541af197b50b8dd8f22642ce0b87f

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-2025-21837
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/uring_cmd.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/87fe1d68842a308998b315c8ed0163a1d639017c
	https://git.kernel.org/stable/c/d6211ebbdaa541af197b50b8dd8f22642ce0b87f