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 C2A8139EF1C; Wed, 7 Oct 2026 14:31:43 +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=1791383508; cv=none; b=LOJMk9deUBtan6YTGfygbuD6ypJPL+VdA4ThrA7Pr+GHFouAXLZEIPJx1w1H7j/WpCjuCRaOWEJY6384io5giTZK0NEmLs7vJnzeE+Y8/YACNzBfjLfXRwLvsGaNAzdlWwfwmePF3r+FcKab9cEbqXOwRgS0TbzuXO0mPZRCOts= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791383508; c=relaxed/simple; bh=EWOXX0pSdVpVw0OMH8V6abkv3BIwXFK0qW0lRd/OYK4=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=e9+xVZGMaE42DzrjY9NeNsIGfxEnnLnrRgo2HNvexzzsr+cTFg217MuL92v1Dhzm/Iu/6iRDhE98WEwmhEFN+hBCLmRU/B6USMqPG9ysFizrseqEDDTKEMlUMUIg/DzUQFP/Le/1r+tdKv12Dg2G7+rrtXCRzIYyd1/Zv6LLMrI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=fvkQA9AR; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="fvkQA9AR" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 42D1D1F0089C; Wed, 7 Oct 2026 14:31:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1791383503; bh=mVdNjo/aJq7ORJIk7eTcpj5IV+csgIa9+cL62v3XkAU=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=fvkQA9ARbrEG6VR4KEwjSRrfOi0xyixaPV0x+kDwWYZW8tFswTwcusfBL4ubBaLSr q3gzEu7CB1dZJDHsMms4vA7Els7Iz+ZaJLDpT1C4lA+y/DKg+pznLTwZGUfNw7VedH Ccd+YUrArLgz094DZKHyqEfzncOzmJBFfx9r97lkfaJf9vSx5ZTK4XqJmYTixv+waz VU/+MkzOKsNDSt3M0Mf5seAOTwsZg3FSAULjFcme7cXczflXB5PJaf3D2/KGXWIyZE pl0fIck59YPsS0hsu2W0QUZw7bP5njy/3ftBJLG5yRwiFLbhM1JAATQwXQnewXD5zo TJgEYa0gSDlHw== Date: Wed, 7 Oct 2026 15:31:37 +0100 From: Simon Horman To: fredrik.nyberg@volvocars.com Cc: Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , linux-usb@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Jose Alonso , stable@vger.kernel.org Subject: Re: [PATCH net] net: usb: ax88179_178a: fix rx frame length for non-last packets Message-ID: <20261007143137.GQ83879@horms.kernel.org> References: <20261002-ax88179-rx-len-v1-1-f01a2a295079@volvocars.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261002-ax88179-rx-len-v1-1-f01a2a295079@volvocars.com> On Fri, Oct 02, 2026 at 02:28:57PM +0200, Fredrik Nyberg via B4 Relay wrote: > From: Fredrik Nyberg > > Commit 4ce62d5b2f7a ("net: usb: ax88179_178a: stop lying about > skb->truesize") replaced skb_clone() with a copy into a new skb for > every packet of a bulk-in transfer except the last one. The copy skips > the 2-byte IP alignment pseudo header but still copies pkt_len bytes, > and pkt_len includes that header. Each of these frames is therefore > delivered with two extra trailing bytes: the 0xeeee pseudo header of > the next slot when the frame ends on an 8-byte boundary, or slot > padding otherwise. The last packet is still trimmed to pkt_len - 2. > > IPv4 and IPv6 trim the extra bytes, so most traffic is unaffected. > Anything that relies on the frame length is not. MACsec takes the ICV > from the last 16 bytes and drops every such frame as InPktsNotValid. In > our setup that was 0.2-1.2% of received MACsec frames, depending on how > many frames shared a transfer, including service discovery multicast. > > Allocate and copy pkt_len - 2 bytes, like the last-packet path. > > Fixes: 4ce62d5b2f7a ("net: usb: ax88179_178a: stop lying about skb->truesize") > Cc: stable@vger.kernel.org > Signed-off-by: Fredrik Nyberg Reviewed-by: Simon Horman