---
id: CVE-2026-80825
title: 'wifi: mt76: mt7925: ensure tx headroom in usb_sdio_tx_prepare_skb'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  wifi: mt76: mt7925: ensure tx headroom in usb_sdio_tx_prepare_skb

  mt7925_usb_sdio_tx_prepare_skb() pushes a TX descriptor and a USB
  header onto every skb and assumes t…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= c948b5da6bbec742b433138e3e3f9537a85af2e5 <
    9a72b180f0575e41471e088e09bddc4b73d6dee2
  - >-
    Linux >= c948b5da6bbec742b433138e3e3f9537a85af2e5 <
    22edb6786127271aeba7abd30f152977c605c6a3
  - >-
    Linux >= c948b5da6bbec742b433138e3e3f9537a85af2e5 <
    8d481f93588932a95f657671d4e1601b90d130cc
  - >-
    Linux >= c948b5da6bbec742b433138e3e3f9537a85af2e5 <
    e5e8fc11a7ac578f16079f855b7fffc1649d053c
  - >-
    Linux >= c948b5da6bbec742b433138e3e3f9537a85af2e5 <
    ef3e34874d2332d0f63e72c2c35ce5c93568c125
  - Linux 6.7
published: '2026-09-04'
updated: '2026-10-19'
sourceUpdated: '2026-10-19T08:44:17.799Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-80825'
references:
  - url: 'https://git.kernel.org/stable/c/9a72b180f0575e41471e088e09bddc4b73d6dee2'
  - url: 'https://git.kernel.org/stable/c/22edb6786127271aeba7abd30f152977c605c6a3'
  - url: 'https://git.kernel.org/stable/c/8d481f93588932a95f657671d4e1601b90d130cc'
  - url: 'https://git.kernel.org/stable/c/e5e8fc11a7ac578f16079f855b7fffc1649d053c'
  - url: 'https://git.kernel.org/stable/c/ef3e34874d2332d0f63e72c2c35ce5c93568c125'
tags:
  - cve.org
epss: 0.00168
epssPercentile: 0.05664
ingestedAt: '2026-10-19T09:16:01.503Z'
---

## Overview

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

wifi: mt76: mt7925: ensure tx headroom in usb_sdio_tx_prepare_skb

mt7925_usb_sdio_tx_prepare_skb() pushes a TX descriptor and a USB
header onto every skb and assumes the headroom for them is already
there. That holds for locally generated traffic, where mac80211
reserves hw->extra_tx_headroom, but forwarded frames are sent through
ieee80211_8023_xmit(), which does not reserve it. Bridge a wired
interface to an mt7925u AP and the first forwarded frame that arrives
short panics the kernel:

 skbuff: skb_under_panic: len:415 put:4 tail:0x19b end:0x640 dev:wlan1
 kernel BUG at net/core/skbuff.c:212!
 Call trace:
  skb_panic+0x58/0x60 (P)
  skb_push+0x58/0x60
  mt7925_usb_sdio_tx_prepare_skb+0xf8/0x1b8 [mt7925_common]
  mt76u_tx_queue_skb+0xa0/0x1f8 [mt76_usb]
  __mt76_tx_queue_skb+0x54/0xe8 [mt76]
  mt76_txq_schedule.part.0+0x204/0x478 [mt76]
  mt76_txq_schedule_all+0x50/0x80 [mt76]
  mt792x_tx_worker+0x68/0x100 [mt792x_lib]
  __mt76_worker_fn+0x84/0x150 [mt76]

Whether a given setup hits it depends on how much headroom the ingress
netdev leaves in its rx skbs. Reproduced on a Raspberry Pi 5 bridging
onboard ethernet to a Netgear A9000; originally reported on an MT7986
router running OpenWrt. Nick Morrow's testing on a Pi 4 (bcmgenet),
which leaves more headroom, helped narrow the trigger to the ingress
path.

The same bug was fixed on mt7921 by commit 98c4d0abf5c4 ("mt76:
mt7921: don't assume adequate headroom for SDIO headers"), but mt7925
was copied from mt7921 without the fix. Add the same guard here.

## Affected

- `Linux >= c948b5da6bbec742b433138e3e3f9537a85af2e5 < 9a72b180f0575e41471e088e09bddc4b73d6dee2`
- `Linux >= c948b5da6bbec742b433138e3e3f9537a85af2e5 < 22edb6786127271aeba7abd30f152977c605c6a3`
- `Linux >= c948b5da6bbec742b433138e3e3f9537a85af2e5 < 8d481f93588932a95f657671d4e1601b90d130cc`
- `Linux >= c948b5da6bbec742b433138e3e3f9537a85af2e5 < e5e8fc11a7ac578f16079f855b7fffc1649d053c`
- `Linux >= c948b5da6bbec742b433138e3e3f9537a85af2e5 < ef3e34874d2332d0f63e72c2c35ce5c93568c125`
- `Linux 6.7`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.