linux-cve-announce - CVE-2025-38688: iommufd: Prevent ALIGN() overflow

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Message-ID: <2025090448-CVE-2025-38688-6e94@gregkh>
Date: Thu,  4 Sep 2025 17:32:53 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-38688: iommufd: Prevent ALIGN() overflow

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

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

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

iommufd: Prevent ALIGN() overflow

When allocating IOVA the candidate range gets aligned to the target
alignment. If the range is close to ULONG_MAX then the ALIGN() can
wrap resulting in a corrupted iova.

Open code the ALIGN() using get_add_overflow() to prevent this.
This simplifies the checks as we don't need to check for length earlier
either.

Consolidate the two copies of this code under a single helper.

This bug would allow userspace to create a mapping that overlaps with some
other mapping or a reserved range.

The Linux kernel CVE team has assigned CVE-2025-38688 to this issue.


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

	Issue introduced in 6.2 with commit 51fe6141f0f64ae0bbc096a41a07572273e8c0ef and fixed in 6.6.103 with commit d19b817540c0abe84854a64ee9ee34cecc3bbeef
	Issue introduced in 6.2 with commit 51fe6141f0f64ae0bbc096a41a07572273e8c0ef and fixed in 6.12.43 with commit ebb6021560b94649bec6b8faba6fe0dca2218e81
	Issue introduced in 6.2 with commit 51fe6141f0f64ae0bbc096a41a07572273e8c0ef and fixed in 6.15.11 with commit e42a046bb41dcdde4f766a17d8211842007ed537
	Issue introduced in 6.2 with commit 51fe6141f0f64ae0bbc096a41a07572273e8c0ef and fixed in 6.16.2 with commit 79fad1917802c28de51a479318a056a6fbe3e2f2
	Issue introduced in 6.2 with commit 51fe6141f0f64ae0bbc096a41a07572273e8c0ef and fixed in 6.17-rc1 with commit b42497e3c0e74db061eafad41c0cd7243c46436b

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-2025-38688
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/io_pagetable.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/d19b817540c0abe84854a64ee9ee34cecc3bbeef
	https://git.kernel.org/stable/c/ebb6021560b94649bec6b8faba6fe0dca2218e81
	https://git.kernel.org/stable/c/e42a046bb41dcdde4f766a17d8211842007ed537
	https://git.kernel.org/stable/c/79fad1917802c28de51a479318a056a6fbe3e2f2
	https://git.kernel.org/stable/c/b42497e3c0e74db061eafad41c0cd7243c46436b