linux-cve-announce - CVE-2026-23109: fs/writeback: skip AS_NO_DATA_INTEGRITY mappings in wait_sb

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Message-ID: <2026020431-CVE-2026-23109-3e57@gregkh>
Date: Wed,  4 Feb 2026 17:15:08 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2026-23109: fs/writeback: skip AS_NO_DATA_INTEGRITY mappings in wait_sb_inodes()

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

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

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

fs/writeback: skip AS_NO_DATA_INTEGRITY mappings in wait_sb_inodes()

Above the while() loop in wait_sb_inodes(), we document that we must wait
for all pages under writeback for data integrity.  Consequently, if a
mapping, like fuse, traditionally does not have data integrity semantics,
there is no need to wait at all; we can simply skip these inodes.

This restores fuse back to prior behavior where syncs are no-ops.  This
fixes a user regression where if a system is running a faulty fuse server
that does not reply to issued write requests, this causes wait_sb_inodes()
to wait forever.

The Linux kernel CVE team has assigned CVE-2026-23109 to this issue.


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

	Issue introduced in 6.16 with commit 0c58a97f919c24fe4245015f4375a39ff05665b6 and fixed in 6.18.8 with commit 3f4ed5e2b8f111553562507ad6202432c7c57731
	Issue introduced in 6.16 with commit 0c58a97f919c24fe4245015f4375a39ff05665b6 and fixed in 6.19-rc7 with commit f9a49aa302a05e91ca01f69031cb79a0ea33031f

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-2026-23109
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/fs-writeback.c
	fs/fuse/file.c
	include/linux/pagemap.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/3f4ed5e2b8f111553562507ad6202432c7c57731
	https://git.kernel.org/stable/c/f9a49aa302a05e91ca01f69031cb79a0ea33031f