CVE-2026-89617: fs/ntfs3: validate dirty page table on log replay

CVE-2026-89617: fs/ntfs3: validate dirty page table on log replay

[Greg Kroah-Hartman]

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

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

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

fs/ntfs3: validate dirty page table on log replay

Each DIR_PAGE_ENTRY ends in a page_lcns[] array whose length is the on-disk
lcns_follow field. check_rstbl() validates the table bookkeeping but never
checks that this array fits in the entry, so a crafted lcns_follow lets the
v0->v1 conversion memmove and later replay passes run off the entry.

Add check_dp_table() to reject, right after check_rstbl(), any entry larger
than its size claims via struct_size() (the same expression used to allocate
these entries, so the check is overflow-safe by construction). All consumers
can then trust lcns_follow as the real capacity. This covers every
page_lcns[] access whose index is bounded by the entry itself (the
conversion memmove, the HotFix store via find_dp(), and the self-bounded
scan loops). Accesses whose index comes from the log record need a separate
bound and are handled in a follow-up patch.

The Linux kernel CVE team has assigned CVE-2026-89617 to this issue.


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

	Issue introduced in 5.15 with commit b46acd6a6a627d876898e1c84d3f84902264b445 and fixed in 6.12.109 with commit 1200c2779c43b62656ccbb67df9468a7a9af2484
	Issue introduced in 5.15 with commit b46acd6a6a627d876898e1c84d3f84902264b445 and fixed in 6.18.50 with commit 2d94ffc9d7b5bb3517b129fe63b52d84bcd4ae56
	Issue introduced in 5.15 with commit b46acd6a6a627d876898e1c84d3f84902264b445 and fixed in 7.2.4 with commit 0908da07c23be4f94b99dfd9a94765525f0fe4bd
	Issue introduced in 5.15 with commit b46acd6a6a627d876898e1c84d3f84902264b445 and fixed in 7.3-rc1 with commit 006cb7713dec10368e699abc4367e5faa334c9a5

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-2026-89617
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/ntfs3/fslog.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/1200c2779c43b62656ccbb67df9468a7a9af2484
	https://git.kernel.org/stable/c/2d94ffc9d7b5bb3517b129fe63b52d84bcd4ae56
	https://git.kernel.org/stable/c/0908da07c23be4f94b99dfd9a94765525f0fe4bd
	https://git.kernel.org/stable/c/006cb7713dec10368e699abc4367e5faa334c9a5