CVE-2026-72197: fs/ntfs3: bound DeleteIndexEntryAllocation memmove length

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

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

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

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

fs/ntfs3: bound DeleteIndexEntryAllocation memmove length

In do_action()'s DeleteIndexEntryAllocation case, e->size comes
from an on-disk INDEX_BUFFER entry.  When e->size makes
e + e->size point past hdr + hdr->used,
PtrOffset(e1, Add2Ptr(hdr, used)) returns a negative ptrdiff_t
that is silently cast to a quasi-infinite size_t when passed
to memmove().  The memmove then walks past the destination
buffer.

The sibling DeleteIndexEntryRoot case at fslog.c:3540-3543
already carries the corresponding guard:

	if (PtrOffset(e1, Add2Ptr(hdr, used)) < esize ||
	    Add2Ptr(e, esize) > Add2Ptr(lrh, rec_len) ||
	    used + esize > le32_to_cpu(hdr->total)) {
		goto dirty_vol;
	}

Apply the same shape to the allocation-path case.  Also reject
esize == 0: memmove(e, e, ...) is a no-op and leaves
hdr->used unchanged, hiding a malformed entry from the
existing check_index_header() walk.

Reproduced under UML+KASAN on mainline 8d90b09e6741 by
mounting a crafted NTFS image: the unguarded memmove takes a
length of 0xffffffffffffff00 and the kernel oopses in
memmove+0x81/0x1a0 on the do_action+0x36a2 frame.

[almaz.alexandrovich@paragon-software.com: clang-formatted the changes]

The Linux kernel CVE team has assigned CVE-2026-72197 to this issue.


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

	Issue introduced in 5.15 with commit b46acd6a6a627d876898e1c84d3f84902264b445 and fixed in 5.15.212 with commit c38ed2ab62fab75fd6d0fdc2bee540fbebc7b959
	Issue introduced in 5.15 with commit b46acd6a6a627d876898e1c84d3f84902264b445 and fixed in 6.1.178 with commit b509b9613f20dc5b653d54bf78fab00d79cc43c8
	Issue introduced in 5.15 with commit b46acd6a6a627d876898e1c84d3f84902264b445 and fixed in 6.6.145 with commit 4c8aac931c1cd70347961ba5157aa916448c6a25
	Issue introduced in 5.15 with commit b46acd6a6a627d876898e1c84d3f84902264b445 and fixed in 6.12.97 with commit f383aae59ec3994c14804f4191c59038b206be81
	Issue introduced in 5.15 with commit b46acd6a6a627d876898e1c84d3f84902264b445 and fixed in 6.18.40 with commit 09fddd52c1b0cef2c086d61be8f3d5dc92e36565
	Issue introduced in 5.15 with commit b46acd6a6a627d876898e1c84d3f84902264b445 and fixed in 7.1.5 with commit 554700c65d398276cb00a8ef95f1d5e00b9eff93
	Issue introduced in 5.15 with commit b46acd6a6a627d876898e1c84d3f84902264b445 and fixed in 7.2-rc1 with commit fc4626bb3656362de8b0ecd56605d47a19ec3518

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-2026-72197
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/c38ed2ab62fab75fd6d0fdc2bee540fbebc7b959
	https://git.kernel.org/stable/c/b509b9613f20dc5b653d54bf78fab00d79cc43c8
	https://git.kernel.org/stable/c/4c8aac931c1cd70347961ba5157aa916448c6a25
	https://git.kernel.org/stable/c/f383aae59ec3994c14804f4191c59038b206be81
	https://git.kernel.org/stable/c/09fddd52c1b0cef2c086d61be8f3d5dc92e36565
	https://git.kernel.org/stable/c/554700c65d398276cb00a8ef95f1d5e00b9eff93
	https://git.kernel.org/stable/c/fc4626bb3656362de8b0ecd56605d47a19ec3518