linux-cve-announce - CVE-2025-39888: fuse: Block access to folio overlimit

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Message-ID: <2025092303-CVE-2025-39888-3c85@gregkh>
Date: Tue, 23 Sep 2025 08:01:19 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-39888: fuse: Block access to folio overlimit

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

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

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

fuse: Block access to folio overlimit

syz reported a slab-out-of-bounds Write in fuse_dev_do_write.

When the number of bytes to be retrieved is truncated to the upper limit
by fc->max_pages and there is an offset, the oob is triggered.

Add a loop termination condition to prevent overruns.

The Linux kernel CVE team has assigned CVE-2025-39888 to this issue.


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

	Issue introduced in 6.16 with commit 3568a956932621cafadafc8b75fcf6dc06555105 and fixed in 6.16.8 with commit 623719227b114d73a2cee45f1b343ced63ce09ec
	Issue introduced in 6.16 with commit 3568a956932621cafadafc8b75fcf6dc06555105 and fixed in 6.17-rc6 with commit 9d81ba6d49a7457784f0b6a71046818b86ec7e44

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-2025-39888
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/fuse/dev.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/623719227b114d73a2cee45f1b343ced63ce09ec
	https://git.kernel.org/stable/c/9d81ba6d49a7457784f0b6a71046818b86ec7e44