CVE-2026-89612: ntfs: reject invalid MFT LCNs from boot sector

CVE-2026-89612: ntfs: reject invalid MFT LCNs from boot sector

[Greg Kroah-Hartman]

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

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

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

ntfs: reject invalid MFT LCNs from boot sector

The NTFS boot sector stores the MFT and MFTMirr locations as unsigned
64-bit LCNs, but parse_ntfs_boot_sector() decoded them into an s64.

A crafted high-bit value could therefore become negative and pass
the existing upper-bound check. The invalid value then propagated into
the MFT zone allocator and could result in an out-of-bounds access to
lcn_empty_bits_per_page.

The Linux kernel CVE team has assigned CVE-2026-89612 to this issue.


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

	Issue introduced in 7.1 with commit 11ccc9107dc460de28af90fac1f42404d9802735 and fixed in 7.2.4 with commit 8f8420b68a6f05ca2b03779d8208814ec539b9e5
	Issue introduced in 7.1 with commit 11ccc9107dc460de28af90fac1f42404d9802735 and fixed in 7.3-rc1 with commit cc9d09fef78410bcd37ac05168cbd5f6dd75d3d2

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-2026-89612
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/ntfs/super.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/8f8420b68a6f05ca2b03779d8208814ec539b9e5
	https://git.kernel.org/stable/c/cc9d09fef78410bcd37ac05168cbd5f6dd75d3d2