CVE-2026-98687: thunderbolt: Reject oversized XDomain properties responses

CVE-2026-98687: thunderbolt: Reject oversized XDomain properties responses

[Greg Kroah-Hartman]

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

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

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

thunderbolt: Reject oversized XDomain properties responses

tb_xdp_properties_request() allocates room for 45 data dwords in its
252-byte response buffer.  The XDomain length field is six bits wide,
however, and a malicious peer can set it to 63.  After the fixed response
fields are subtracted, the driver treats this as 48 data dwords.

Commit 322e93448d90 ("thunderbolt: Clamp XDomain response data copy to
allocation size") only bounds the copy against data_len.  If data_len is
at least 48, memcpy() reads 192 bytes from the 180-byte res->data array,
causing a 12-byte heap out-of-bounds read.  Commit 4db2bd2ed478
("thunderbolt: Limit XDomain response copy to actual frame size") limits
the earlier copy but does not constrain this header-derived length.

Reject response data lengths that exceed the allocated source buffer
before copying them into the assembled property block.

The Linux kernel CVE team has assigned CVE-2026-98687 to this issue.


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

	Issue introduced in 4.15 with commit d1ff70241a275133e1a0258b7c23588b122276c8 and fixed in 6.12.113 with commit a766a86ff48acee76aeb8e2575771040749e509d
	Issue introduced in 4.15 with commit d1ff70241a275133e1a0258b7c23588b122276c8 and fixed in 6.18.56 with commit 2f97f929dad9eb3e1f63b721d2dd49bf9bc68efa
	Issue introduced in 4.15 with commit d1ff70241a275133e1a0258b7c23588b122276c8 and fixed in 7.2.10 with commit 737a1d2e9642d5f718bd29aa4a98b9eef3832f0a
	Issue introduced in 4.15 with commit d1ff70241a275133e1a0258b7c23588b122276c8 and fixed in 7.3-rc6 with commit 80756e263846ab694984e749e8c626897331438f

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-2026-98687
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:
	drivers/thunderbolt/xdomain.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/a766a86ff48acee76aeb8e2575771040749e509d
	https://git.kernel.org/stable/c/2f97f929dad9eb3e1f63b721d2dd49bf9bc68efa
	https://git.kernel.org/stable/c/737a1d2e9642d5f718bd29aa4a98b9eef3832f0a
	https://git.kernel.org/stable/c/80756e263846ab694984e749e8c626897331438f