linux-cve-announce - CVE-2025-40293: iommufd: Don't overflow during division for dirty tracking

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Message-ID: <2025120818-CVE-2025-40293-cfe7@gregkh>
Date: Mon,  8 Dec 2025 09:47:18 +0900
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-40293: iommufd: Don't overflow during division for dirty tracking

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

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

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

iommufd: Don't overflow during division for dirty tracking

If pgshift is 63 then BITS_PER_TYPE(*bitmap->bitmap) * pgsize will overflow
to 0 and this triggers divide by 0.

In this case the index should just be 0, so reorganize things to divide
by shift and avoid hitting any overflows.

The Linux kernel CVE team has assigned CVE-2025-40293 to this issue.


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

	Issue introduced in 6.1 with commit 58ccf0190d19d9a8a41f8a02b9e06742b58df4a1 and fixed in 6.1.159 with commit 07105e61882ff4a7d58db63cc5f9e90c6c60506c
	Issue introduced in 6.1 with commit 58ccf0190d19d9a8a41f8a02b9e06742b58df4a1 and fixed in 6.6.117 with commit 4c8a4f1d34eced168cc0b3a3dfe7b6dcc2090f69
	Issue introduced in 6.1 with commit 58ccf0190d19d9a8a41f8a02b9e06742b58df4a1 and fixed in 6.12.58 with commit de7f2c67ceb1941b05b04ac35458a03e93cc57b1
	Issue introduced in 6.1 with commit 58ccf0190d19d9a8a41f8a02b9e06742b58df4a1 and fixed in 6.17.8 with commit dbf316fc90aa954dcd5440817f4b944627ed63e0
	Issue introduced in 6.1 with commit 58ccf0190d19d9a8a41f8a02b9e06742b58df4a1 and fixed in 6.18 with commit cb30dfa75d55eced379a42fd67bd5fb7ec38555e

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-2025-40293
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:
	drivers/iommu/iommufd/iova_bitmap.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/07105e61882ff4a7d58db63cc5f9e90c6c60506c
	https://git.kernel.org/stable/c/4c8a4f1d34eced168cc0b3a3dfe7b6dcc2090f69
	https://git.kernel.org/stable/c/de7f2c67ceb1941b05b04ac35458a03e93cc57b1
	https://git.kernel.org/stable/c/dbf316fc90aa954dcd5440817f4b944627ed63e0
	https://git.kernel.org/stable/c/cb30dfa75d55eced379a42fd67bd5fb7ec38555e