From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-cve-announce@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@kernel.org>
Subject: CVE-2026-89614: ntfs: bound the free-cluster bitmap scan to the volume
Date: Fri, 11 Sep 2026 21:45:03 +0200 [thread overview]
Message-ID: <2026091135-CVE-2026-89614-db97@gregkh> (raw)
From: Greg Kroah-Hartman <gregkh@kernel.org>
Description
===========
In the Linux kernel, the following vulnerability has been resolved:
ntfs: bound the free-cluster bitmap scan to the volume
vol->lcn_empty_bits_per_page is sized from vol->nr_clusters at mount, but
ntfs_cluster_alloc() bounds its scan of that array by the size of $Bitmap.
Those are independent on-disk quantities and the mount-time check only
rejects a $Bitmap that is too small, so an image whose $Bitmap covers more
clusters than the volume has lets the scan index past the array. A run
whose LCN lies in that gap takes the allocator straight there, since the
caller passes the file's own last LCN as its locality hint. KASAN reports
a slab out-of-bounds read when a file on such a volume is extended.
Clamp the scan to what that array covers, mirroring the max_index
calculation the mount-time scan already uses, and reject a decoded LCN
at or beyond nr_clusters in the mapping pairs decoder. Conforming
volumes are unaffected.
The Linux kernel CVE team has assigned CVE-2026-89614 to this issue.
Affected and fixed versions
===========================
Issue introduced in 7.1 with commit 11ccc9107dc460de28af90fac1f42404d9802735 and fixed in 7.2.4 with commit dc15a9f5307d5372aef3b64bf3ed7802f530c471
Issue introduced in 7.1 with commit 11ccc9107dc460de28af90fac1f42404d9802735 and fixed in 7.3-rc1 with commit 19cac7902a8ab748e15f98ddaafcf5f8882be21d
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-2026-89614
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/lcnalloc.c
fs/ntfs/runlist.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/dc15a9f5307d5372aef3b64bf3ed7802f530c471
https://git.kernel.org/stable/c/19cac7902a8ab748e15f98ddaafcf5f8882be21d
reply other threads:[~2026-09-11 19:58 UTC|newest]
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