GHSA-82XC-6PQJ-MVC4
Vulnerability from github – Published: 2026-09-04 18:31 – Updated: 2026-09-04 18:31In 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": [],
"aliases": [
"CVE-2026-80825"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-04T16:18:10Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nwifi: mt76: mt7925: ensure tx headroom in usb_sdio_tx_prepare_skb\n\nmt7925_usb_sdio_tx_prepare_skb() pushes a TX descriptor and a USB\nheader onto every skb and assumes the headroom for them is already\nthere. That holds for locally generated traffic, where mac80211\nreserves hw-\u003eextra_tx_headroom, but forwarded frames are sent through\nieee80211_8023_xmit(), which does not reserve it. Bridge a wired\ninterface to an mt7925u AP and the first forwarded frame that arrives\nshort panics the kernel:\n\n skbuff: skb_under_panic: len:415 put:4 tail:0x19b end:0x640 dev:wlan1\n kernel BUG at net/core/skbuff.c:212!\n Call trace:\n skb_panic+0x58/0x60 (P)\n skb_push+0x58/0x60\n mt7925_usb_sdio_tx_prepare_skb+0xf8/0x1b8 [mt7925_common]\n mt76u_tx_queue_skb+0xa0/0x1f8 [mt76_usb]\n __mt76_tx_queue_skb+0x54/0xe8 [mt76]\n mt76_txq_schedule.part.0+0x204/0x478 [mt76]\n mt76_txq_schedule_all+0x50/0x80 [mt76]\n mt792x_tx_worker+0x68/0x100 [mt792x_lib]\n __mt76_worker_fn+0x84/0x150 [mt76]\n\nWhether a given setup hits it depends on how much headroom the ingress\nnetdev leaves in its rx skbs. Reproduced on a Raspberry Pi 5 bridging\nonboard ethernet to a Netgear A9000; originally reported on an MT7986\nrouter running OpenWrt. Nick Morrow\u0027s testing on a Pi 4 (bcmgenet),\nwhich leaves more headroom, helped narrow the trigger to the ingress\npath.\n\nThe same bug was fixed on mt7921 by commit 98c4d0abf5c4 (\"mt76:\nmt7921: don\u0027t assume adequate headroom for SDIO headers\"), but mt7925\nwas copied from mt7921 without the fix. Add the same guard here.",
"id": "GHSA-82xc-6pqj-mvc4",
"modified": "2026-09-04T18:31:27Z",
"published": "2026-09-04T18:31:27Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-80825"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/22edb6786127271aeba7abd30f152977c605c6a3"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/8d481f93588932a95f657671d4e1601b90d130cc"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/9a72b180f0575e41471e088e09bddc4b73d6dee2"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e5e8fc11a7ac578f16079f855b7fffc1649d053c"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/ef3e34874d2332d0f63e72c2c35ce5c93568c125"
}
],
"schema_version": "1.4.0",
"severity": []
}
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