CVE-2026-68311: wifi: mt76: mt7925: guard link STA in decap offload

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

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

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

wifi: mt76: mt7925: guard link STA in decap offload

mt7925_sta_set_decap_offload() iterates over the vif valid_links mask
when updating decap offload state for an MLO station. The station may not
have a link STA for every valid link of the vif, so mt792x_sta_to_link()
can return NULL for a link that belongs to the vif but not to the station.

The function currently dereferences mlink before checking whether the
link WCID is ready. If mlink is NULL, setting or clearing
MT_WCID_FLAG_HDR_TRANS dereferences a NULL pointer.

Skip links without a station link before touching mlink->wcid.

The Linux kernel CVE team has assigned CVE-2026-68311 to this issue.


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

	Issue introduced in 6.11 with commit b859ad65309a5f1654e8b284de582831fc88e2d8 and fixed in 6.12.101 with commit 1e608cae1ba0b4a600b752efa223fd2be376b143
	Issue introduced in 6.11 with commit b859ad65309a5f1654e8b284de582831fc88e2d8 and fixed in 6.18.42 with commit f1ee53e08fdd2906e90c6a6d71e1368fcd52bfc3
	Issue introduced in 6.11 with commit b859ad65309a5f1654e8b284de582831fc88e2d8 and fixed in 7.1.6 with commit d86883f7e8f03a5b81b4e59f2c0b6c05f79e01fd
	Issue introduced in 6.11 with commit b859ad65309a5f1654e8b284de582831fc88e2d8 and fixed in 7.2-rc5 with commit 96ea44f2269f30364cffa054ee3a87e595bef0d4

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-2026-68311
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/net/wireless/mediatek/mt76/mt7925/main.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/1e608cae1ba0b4a600b752efa223fd2be376b143
	https://git.kernel.org/stable/c/f1ee53e08fdd2906e90c6a6d71e1368fcd52bfc3
	https://git.kernel.org/stable/c/d86883f7e8f03a5b81b4e59f2c0b6c05f79e01fd
	https://git.kernel.org/stable/c/96ea44f2269f30364cffa054ee3a87e595bef0d4