linux-cve-announce - CVE-2026-23223: xfs: fix UAF in xchk_btree_check_block

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Message-ID: <2026021806-CVE-2026-23223-e3d3@gregkh>
Date: Wed, 18 Feb 2026 15:54:12 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2026-23223: xfs: fix UAF in xchk_btree_check_block_owner

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

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

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

xfs: fix UAF in xchk_btree_check_block_owner

We cannot dereference bs->cur when trying to determine if bs->cur
aliases bs->sc->sa.{bno,rmap}_cur after the latter has been freed.
Fix this by sampling before type before any freeing could happen.
The correct temporal ordering was broken when we removed xfs_btnum_t.

The Linux kernel CVE team has assigned CVE-2026-23223 to this issue.


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

	Fixed in 6.12.72 with commit 1d411278dda293a507cb794db7d9ed3511c685c6
	Fixed in 6.18.11 with commit ed82e7949f5cac3058f4100f3cd670531d41a266
	Fixed in 6.19.1 with commit ba5264610423d9653aa36920520902d83841bcfd

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-2026-23223
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:
	fs/xfs/scrub/btree.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/1d411278dda293a507cb794db7d9ed3511c685c6
	https://git.kernel.org/stable/c/ed82e7949f5cac3058f4100f3cd670531d41a266
	https://git.kernel.org/stable/c/ba5264610423d9653aa36920520902d83841bcfd
	https://git.kernel.org/stable/c/1c253e11225bc5167217897885b85093e17c2217