CVE-2026-90048: fs/ntfs3: fix slab-out-of-bounds write in ni_create_attr_list()

CVE-2026-90048: fs/ntfs3: fix slab-out-of-bounds write in ni_create_attr_list()

[Greg Kroah-Hartman]

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

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

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

fs/ntfs3: fix slab-out-of-bounds write in ni_create_attr_list()

ni_create_attr_list() allocates a fixed buffer of al_aligned(record_size)
(== record_size) bytes and then walks every attribute of the primary MFT
record, writing one ATTR_LIST_ENTRY per attribute and advancing the cursor
by le_size(name_len), with no check against the end of the buffer; the
total size is only computed after the loop.

A minimum-size resident attribute occupies SIZEOF_RESIDENT (0x18 = 24)
bytes on disk, but an unnamed attribute expands to le_size(0) (0x20 = 32)
bytes in the list.  Because the number of attributes in a record is not
bounded (mi_enum_attr() accepts arbitrarily many equal-type, nameless
minimum-size attributes), a crafted record packed with such attributes
produces a list larger than record_size and overflows the heap buffer.

This is reachable from a crafted, loop-mounted NTFS image: opening the file
and adding an attribute (e.g. via setxattr) drives ntfs_set_ea() ->
ni_insert_resident() -> ni_insert_attr() -> ni_ins_attr_ext() ->
ni_create_attr_list().

  BUG: KASAN: slab-out-of-bounds in ni_create_attr_list+0xc48/0x1058
  Write of size 4 at addr ffff000008984c00 by task setfattr/345
   ni_create_attr_list+0xc48/0x1058
   ni_ins_attr_ext+0x510/0x7c0
   ni_insert_attr+0x3f8/0x70c
   ni_insert_resident+0xc8/0x3b0
   ntfs_set_ea+0x66c/0xd28
   ntfs_setxattr+0x4d8/0x5b0
   __arm64_sys_setxattr+0xa4/0x124
  Allocated by task 345:
   ni_create_attr_list+0x188/0x1058
  The buggy address belongs to the cache kmalloc-1k of size 1024
  (the write lands at object+1024).

Size the buffer from the actual attributes instead of assuming a single
record_size is always enough.

The Linux kernel CVE team has assigned CVE-2026-90048 to this issue.


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

	Issue introduced in 5.15 with commit 4342306f0f0d5ff4315a204d315c1b51b914fca5 and fixed in 6.6.157 with commit 7e9aee7e4d9767cc3e423b3beecb01c7ebb6bbcd
	Issue introduced in 5.15 with commit 4342306f0f0d5ff4315a204d315c1b51b914fca5 and fixed in 6.12.110 with commit fa2215cf451414b0512cd6f7d37a057893811f4d
	Issue introduced in 5.15 with commit 4342306f0f0d5ff4315a204d315c1b51b914fca5 and fixed in 6.18.51 with commit d07e281f2a7710502985d6f80b95ddac8f4e81d5
	Issue introduced in 5.15 with commit 4342306f0f0d5ff4315a204d315c1b51b914fca5 and fixed in 7.2.5 with commit a84f3db72561c4d9281c5ff721ce46b9ffa7f30e
	Issue introduced in 5.15 with commit 4342306f0f0d5ff4315a204d315c1b51b914fca5 and fixed in 7.3-rc1 with commit 7c4841e2a62794a3bab7c1ff0540580f387e377f

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-2026-90048
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/frecord.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/7e9aee7e4d9767cc3e423b3beecb01c7ebb6bbcd
	https://git.kernel.org/stable/c/fa2215cf451414b0512cd6f7d37a057893811f4d
	https://git.kernel.org/stable/c/d07e281f2a7710502985d6f80b95ddac8f4e81d5
	https://git.kernel.org/stable/c/a84f3db72561c4d9281c5ff721ce46b9ffa7f30e
	https://git.kernel.org/stable/c/7c4841e2a62794a3bab7c1ff0540580f387e377f