CVE-2026-68343: smb: client: validate DFS referral PathConsumed

From: Greg Kroah-Hartman <[email protected]>

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

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

smb: client: validate DFS referral PathConsumed

parse_dfs_referrals() validates that the response contains the fixed
referral entry array and, on for-next, the per-referral string offsets.
However, the response also contains a PathConsumed value that is later
used for DFS path parsing.

If a malformed response provides a PathConsumed value larger than the
search name, later DFS parsing can advance beyond the end of the path.

Validate PathConsumed against the search name length before storing it in
the parsed referral.

The Linux kernel CVE team has assigned CVE-2026-68343 to this issue.


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

	Issue introduced in 4.11 with commit 4ecce920e13ace16a5ba45efe8909946c28fb2ad and fixed in 6.6.148 with commit 5b439f39f33ec15d319ced3b025e122346fba987
	Issue introduced in 4.11 with commit 4ecce920e13ace16a5ba45efe8909946c28fb2ad and fixed in 6.12.101 with commit 285bd4a5f3f156aa5869843b47a1b1380b774241
	Issue introduced in 4.11 with commit 4ecce920e13ace16a5ba45efe8909946c28fb2ad and fixed in 6.18.42 with commit 2fdd6d196c656b376cc251e1e9ff110b3ed522e1
	Issue introduced in 4.11 with commit 4ecce920e13ace16a5ba45efe8909946c28fb2ad and fixed in 7.1.6 with commit 9f88a99ed511651b2dc2177d6854b2d1b8322e75
	Issue introduced in 4.11 with commit 4ecce920e13ace16a5ba45efe8909946c28fb2ad and fixed in 7.2-rc5 with commit f6f5ee2aa33b350c671721b965251c42cebb962e

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-2026-68343
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/smb/client/misc.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/5b439f39f33ec15d319ced3b025e122346fba987
	https://git.kernel.org/stable/c/285bd4a5f3f156aa5869843b47a1b1380b774241
	https://git.kernel.org/stable/c/2fdd6d196c656b376cc251e1e9ff110b3ed522e1
	https://git.kernel.org/stable/c/9f88a99ed511651b2dc2177d6854b2d1b8322e75
	https://git.kernel.org/stable/c/f6f5ee2aa33b350c671721b965251c42cebb962e