From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 25E734A6CEC; Mon, 31 Aug 2026 13:45:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788183907; cv=none; b=ZccVIn2/GuiS6CLT6qssdhhChNUg53elmGX40PrIecDnz9Jhu3+9cJjfv/a1Jp5qTgHSaFzWZNh6tXvOclRw8hGTfssvkbW41e0M0Ztp8vQIX3WdVVb9a93t7ZOUeWbWRmpxGRHknrc0l9Y/pxu9LiJL6Vv83HbfmF/u+d75c3U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788183907; c=relaxed/simple; bh=J45QPd1wMpZ/W7CtSO08CQah/nlQZukNZUflso1nQkk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=LD2mPbuzaF3HyesjAg6OrjhWE1e0EAlDNMbarlFt+y5lGZWep8qqV1hRrrft2W+1U6SxHn2/bOl6LuW+iJta+LVUii3VN6i8abi1XtLE8s3GosWujU0LHvPpnzAjD8SGiqRRC/By91p63LJB7i/VtmRaw5bvhJXNzQ18tff8Q2A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=0S/3MV3d; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="0S/3MV3d" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4F9ED1F00A3E; Mon, 31 Aug 2026 13:45:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788183903; bh=hJk0GILinPgCM7rO3l/9ikaCxkbCvEut5RBvTiSburY=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=0S/3MV3dGgGyRlG2rRvgHkqEkvvidJfCIjE6AS+8K0tUGVil47cj1NEXn6TrdXJJr PRmWkcnMYj+obqJQ0qC7oJ1w6g5V02m0KV8KAt37QUjC1p9KJCKT0Y/d37GB3ugpzz 1Kv4yviBFv579ZuSSsr89U5P2m466EHqdCubQo00= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Devin Wittmayer , Felix Fietkau Subject: [PATCH 7.1 75/76] wifi: mt76: mt7925: ensure tx headroom in usb_sdio_tx_prepare_skb Date: Mon, 31 Aug 2026 15:34:47 +0200 Message-ID: <20260831133403.238072818@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260831133359.185608553@linuxfoundation.org> References: <20260831133359.185608553@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 7.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Devin Wittmayer commit ef3e34874d2332d0f63e72c2c35ce5c93568c125 upstream. 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. Fixes: c948b5da6bbe ("wifi: mt76: mt7925: add Mediatek Wi-Fi7 driver for mt7925 chips") Cc: stable@vger.kernel.org Link: https://github.com/morrownr/mt76/issues/52 Signed-off-by: Devin Wittmayer Link: https://patch.msgid.link/20260715023348.59506-1-lucid_duck@justthetip.ca Signed-off-by: Felix Fietkau Signed-off-by: Greg Kroah-Hartman --- drivers/net/wireless/mediatek/mt76/mt7925/mac.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/drivers/net/wireless/mediatek/mt76/mt7925/mac.c +++ b/drivers/net/wireless/mediatek/mt76/mt7925/mac.c @@ -1425,6 +1425,10 @@ int mt7925_usb_sdio_tx_prepare_skb(struc if (!wcid) wcid = &dev->mt76.global_wcid; + err = skb_cow_head(skb, MT_SDIO_TXD_SIZE + MT_SDIO_HDR_SIZE); + if (err) + return err; + if (sta) { struct mt792x_sta *msta = (struct mt792x_sta *)sta->drv_priv;