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 86AFE43E080; Mon, 17 Aug 2026 13:44:43 +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=1786974287; cv=none; b=mc5LSdtfSMquomB0fgUSdNUUjtj8txmbO5hhMx0XqDaG8wTCrrNARuxHK1eJJ4o6pAs1OHtkIUamZ5l1xmyhpeq3O6/8w+eSj9P16CZ1rBwX4M6eNRzRqWbbovciqs0PIwRnSiqymcyjp34/ea1cF73SdUtSd8HdVzq5IX0CPf4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786974287; c=relaxed/simple; bh=6L6P6uhXIXFXLOA8/YAaGRX0cxcN0jPZrXT97DDZQe4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=qvCBs4HF+GtXENrBWi2SLszBb4hPvs+C3Gk96ktpe9TtiYmiYOW0IkGO7LbN/J2+c6ZgnBLcF7fW3IQdpzyriN35479dUShi+F4V6sqw2Pq/GcfLPUZJDOQXha0CPmEKSKweH0BxHnBbmOcth8Dm15CYrtNzvyuKJdER188XFms= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=ag8AaAvo; 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="ag8AaAvo" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D7C021F00A3E; Mon, 17 Aug 2026 13:44:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1786974283; bh=/B0/defsZoaJqkLgA1ZaeaIPTnCYTBkU2dv9SrVwLQk=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=ag8AaAvoHjsvxbcUK2gJq/Esx3thuGk7V+E0c/Wtwx0/iqr6W10IGt74KtnXmCXD4 ZYN05gQdsbbwZ0BmxBiPkOhF9zW+eGmaaqqg4wvTMbcBJWsc6H/IrtXEvhLeZi+BP/ snEYhVuvIj1+10H+mvvS8dy3V+WuzbMLVI2RjK4o= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Doruk Tan Ozturk , Willem de Bruijn , Jakub Kicinski Subject: [PATCH 7.1 151/271] net/packet: reset the MAC header on the packet-socket transmit path Date: Mon, 17 Aug 2026 15:31:16 +0200 Message-ID: <20260817132543.106964506@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260817132536.752504388@linuxfoundation.org> References: <20260817132536.752504388@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org 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: Doruk Tan Ozturk commit c2707480cfbf19c7619acc9c089d17f20869821f upstream. packet_parse_headers() resets the MAC header only for a SOCK_RAW frame whose socket did not bind a protocol. A protocol-bound SOCK_RAW socket, any SOCK_DGRAM frame, and the legacy SOCK_PACKET path therefore leave skb->mac_header unset here. For frames sent via __dev_queue_xmit() this is harmless: it resets the MAC header unconditionally. But the packet-socket PACKET_QDISC_BYPASS path uses dev_direct_xmit(), which does not, so the frame reaches ndo_start_xmit() with the MAC header unset. A driver that reads eth_hdr(skb) on transmit then dereferences skb->head + (u16)~0, an out-of-bounds access ~64 KiB past the head -- the same class fixed for one consumer in commit f5089008f90c ("macsec: do not read an unset MAC header in macsec_encrypt()"). packet_parse_headers() runs only on the transmit path, where skb->data points at the start of the L2 header for every packet-socket type regardless of its length: SOCK_RAW and SOCK_PACKET carry a user-supplied header and SOCK_DGRAM has one built by dev_hard_header(). Reset the MAC header unconditionally, mirroring __dev_queue_xmit(), so the frame is anchored on the bypass path too. Found by 0sec (https://0sec.ai) using automated source analysis; verified against source and matched to the macsec KASAN report in f5089008f90c. Compile-tested. Fixes: 75c65772c3d1 ("net/packet: Ask driver for protocol if not provided by user") Cc: stable@vger.kernel.org Signed-off-by: Doruk Tan Ozturk Reviewed-by: Willem de Bruijn Link: https://patch.msgid.link/20260724144015.63219-1-doruk@0sec.ai Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- net/packet/af_packet.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -1924,11 +1924,12 @@ static void packet_parse_headers(struct { int depth; + /* On TX skb->data is the L2 header; anchor it for all socket types. */ + skb_reset_mac_header(skb); + if ((!skb->protocol || skb->protocol == htons(ETH_P_ALL)) && - sock->type == SOCK_RAW) { - skb_reset_mac_header(skb); + sock->type == SOCK_RAW) skb->protocol = dev_parse_header_protocol(skb); - } /* Move network header to the right position for VLAN tagged packets */ if (likely(skb->dev->type == ARPHRD_ETHER) &&