linux-cve-announce - CVE-2025-68350: exfat: fix divide-by-zero in exfat_allocate

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Message-ID: <2025122454-CVE-2025-68350-c55b@gregkh>
Date: Wed, 24 Dec 2025 11:34:55 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-68350: exfat: fix divide-by-zero in exfat_allocate_bitmap

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

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

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

exfat: fix divide-by-zero in exfat_allocate_bitmap

The variable max_ra_count can be 0 in exfat_allocate_bitmap(),
which causes a divide-by-zero error in the subsequent modulo operation
(i % max_ra_count), leading to a system crash.
When max_ra_count is 0, it means that readahead is not used. This patch
load the bitmap without readahead.

The Linux kernel CVE team has assigned CVE-2025-68350 to this issue.


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

	Issue introduced in 6.18 with commit 9fd688678dd86e3be32a35e3b2c5cc3ef0c4e257 and fixed in 6.18.2 with commit 88fc3dd6e631b3e2975f898c6c2b6bc6f7058b44
	Issue introduced in 6.18 with commit 9fd688678dd86e3be32a35e3b2c5cc3ef0c4e257 and fixed in 6.19-rc1 with commit d70a5804c563b5e34825353ba9927509df709651

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-2025-68350
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/exfat/balloc.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/88fc3dd6e631b3e2975f898c6c2b6bc6f7058b44
	https://git.kernel.org/stable/c/d70a5804c563b5e34825353ba9927509df709651