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 E24794DDB2B; Wed, 30 Sep 2026 18:36:12 +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=1790793374; cv=none; b=ozIYRFSFN7FbzMKuZCDtCo5NITO7QByrUw7Pxp4jllk43dxpM4RUVkhrIHbosDoeekIuXI55PjLgDTrXALOS4xfig98O7yaNJH0B93aRhdbhPn4INP1+nSfoXuK1HVevkUd/he6N93HG/+kRUaC3c89wa4ww2+1gdee4o1QbTYI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790793374; c=relaxed/simple; bh=FE/n8A6Zh+6y8BMZZQ1txwEbWm2QhXFfl3QY5NDrgeE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=eSCKu3WupspwlqJ6Eb+0bu7RvgfSQm71bp2GgOm+qxQZP7w8XDd9jKMXrwECmNMIFnQ2KBHp4ul0Re/TZcU9k24q7rzSuvwbk4AzErJ38U7CsGFKgxZFIw2j/ju7phmAAUJL/O+/x/N4QhbCVGpXR6quQIyPw8F6S2+TELQpRTU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=p0AJT2l0; 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="p0AJT2l0" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4CF691F000FF; Wed, 30 Sep 2026 18:36:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790793372; bh=iZWgeBozh+NYzfUfkOkt42S4DdkJUIPcs8nymyrzsM0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=p0AJT2l0pQHHMzWNatLFeROm32PzWlKQLuW3uibjAZqkCM4pW+Tg9CWoPfheEJ9rN h/E/MzAX0M9DCxLHsovjHlEzPEjMaq3lGIG4bqzudwPKJ7HpOl7mRiwAM0KJkTrcfZ MUe1w7BJHxc/XZfyzJMwYBGs/Pt5tYrGq+uPnxcg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, VEGA , Zixuan Chai , Ren Wei , Eric Dumazet , Jakub Kicinski Subject: [PATCH 6.18 233/395] llc: reserve device headroom for allocated frames Date: Wed, 30 Sep 2026 17:28:15 +0200 Message-ID: <20260930152345.716529790@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260930152340.591469096@linuxfoundation.org> References: <20260930152340.591469096@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 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Zixuan Chai commit 72b5b9a28b996e09b8b5b944370c79851bb68f52 upstream. llc_alloc_frame() reserves link-layer headroom using the device type. This is insufficient for stacked Ethernet devices such as VLAN devices, where vlan_dev_hard_header() pushes a VLAN header before the lower device's Ethernet header. An LLC response on such a device can therefore underflow skb headroom in eth_header(). Use LL_RESERVED_SPACE() to account for the device's actual required headroom while preserving the existing LLC device-type check. Fixes: bf9ae5386bca ("llc: use dev_hard_header") Cc: stable@vger.kernel.org Reported-by: VEGA Signed-off-by: Zixuan Chai Signed-off-by: Ren Wei Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20260924012613.2533934-1-weir@nebusec.ai Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- net/llc/llc_sap.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) --- a/net/llc/llc_sap.c +++ b/net/llc/llc_sap.c @@ -25,12 +25,12 @@ #include #include -static int llc_mac_header_len(unsigned short devtype) +static int llc_mac_header_len(struct net_device *dev) { - switch (devtype) { + switch (dev->type) { case ARPHRD_ETHER: case ARPHRD_LOOPBACK: - return sizeof(struct ethhdr); + return LL_RESERVED_SPACE(dev); } return 0; } @@ -51,7 +51,7 @@ struct sk_buff *llc_alloc_frame(struct s int hlen = type == LLC_PDU_TYPE_U ? 3 : 4; struct sk_buff *skb; - hlen += llc_mac_header_len(dev->type); + hlen += llc_mac_header_len(dev); skb = alloc_skb(hlen + data_size, GFP_ATOMIC); if (skb) {