linux-cve-announce - CVE-2025-37804: io_uring: always do atomic put from iowq

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Message-ID: <2025050814-CVE-2025-37804-9c2b@gregkh>
Date: Thu,  8 May 2025 08:39:13 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-37804: io_uring: always do atomic put from iowq

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

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

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

io_uring: always do atomic put from iowq

io_uring always switches requests to atomic refcounting for iowq
execution before there is any parallilism by setting REQ_F_REFCOUNT,
and the flag is not cleared until the request completes. That should be
fine as long as the compiler doesn't make up a non existing value for
the flags, however KCSAN still complains when the request owner changes
oter flag bits:

BUG: KCSAN: data-race in io_req_task_cancel / io_wq_free_work
...
read to 0xffff888117207448 of 8 bytes by task 3871 on cpu 0:
 req_ref_put_and_test io_uring/refs.h:22 [inline]

Skip REQ_F_REFCOUNT checks for iowq, we know it's set.

The Linux kernel CVE team has assigned CVE-2025-37804 to this issue.

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

	Fixed in 6.6.89 with commit c5d4d103005d8926cdad344f9fc947e651c9f2f7
	Fixed in 6.12.26 with commit 3568fd9e440ea393c7d8bee253419ea11fd8e9d9
	Fixed in 6.14.5 with commit 6d2753b46452a557a12f7ef1ef4ee6641b4e89d8
	Fixed in 6.15-rc1 with commit 390513642ee6763c7ada07f0a1470474986e6c1c

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-2025-37804
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/io_uring.c
	io_uring/refs.h

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/c5d4d103005d8926cdad344f9fc947e651c9f2f7
	https://git.kernel.org/stable/c/3568fd9e440ea393c7d8bee253419ea11fd8e9d9
	https://git.kernel.org/stable/c/6d2753b46452a557a12f7ef1ef4ee6641b4e89d8
	https://git.kernel.org/stable/c/390513642ee6763c7ada07f0a1470474986e6c1c