CVE-2026-68193: wifi: mt76: mt7925: drop TXRX_NOTIFY on non-mmio buses

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

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

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

wifi: mt76: mt7925: drop TXRX_NOTIFY on non-mmio buses

PKT_TYPE_TXRX_NOTIFY is an mmio-only event, but mt7925_rx_check() and
mt7925_queue_rx_skb() dispatch it to mt7925_mac_tx_free() on every bus.
mt7925_mac_tx_free() cleans the DMA tx queues with
mt76_queue_tx_cleanup(), which calls queue_ops->tx_cleanup(). Only the
mmio queue ops implement that callback; on USB it is NULL, so a
TXRX_NOTIFY there calls a NULL pointer in the RX worker:

  BUG: kernel NULL pointer dereference, address: 0000000000000000
  RIP: 0010:0x0
  Call Trace:
   mt7925_mac_tx_free+0x58/0x350 [mt7925_common]
   mt7925_rx_check+0xe2/0x130 [mt7925_common]
   mt76u_rx_worker+0x1b9/0x620 [mt76_usb]

Drop the event on non-mmio buses via mt76_is_mmio(), as in
commit 5683e1488aa9 ("wifi: mt76: connac: do not check WED status for
non-mmio devices").

The Linux kernel CVE team has assigned CVE-2026-68193 to this issue.


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

	Issue introduced in 6.7 with commit c948b5da6bbec742b433138e3e3f9537a85af2e5 and fixed in 6.12.101 with commit 0c8c4cd0ca60b45c4b05a39e3769b8473d6836eb
	Issue introduced in 6.7 with commit c948b5da6bbec742b433138e3e3f9537a85af2e5 and fixed in 6.18.42 with commit 9cb72f67e1502aabba51aab9ac04ae7c386ee194
	Issue introduced in 6.7 with commit c948b5da6bbec742b433138e3e3f9537a85af2e5 and fixed in 7.1.6 with commit 9677e86a5f7d680fe280a5f8999bc57353e360d7
	Issue introduced in 6.7 with commit c948b5da6bbec742b433138e3e3f9537a85af2e5 and fixed in 7.2-rc5 with commit feeff151c83e7f0ffcdedcad5343852d23d1f6e1

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-2026-68193
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/mac.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/0c8c4cd0ca60b45c4b05a39e3769b8473d6836eb
	https://git.kernel.org/stable/c/9cb72f67e1502aabba51aab9ac04ae7c386ee194
	https://git.kernel.org/stable/c/9677e86a5f7d680fe280a5f8999bc57353e360d7
	https://git.kernel.org/stable/c/feeff151c83e7f0ffcdedcad5343852d23d1f6e1