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 D5E773A8746; Tue, 16 Jun 2026 16:26:22 +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=1781627183; cv=none; b=OaIyDJ7X/IgRuym9WS2qVSPFWiaSG5BqIbzBZdFxhjAfshZ+iBXTsuJLZoFq8EV8beVO6CWERPv83gNdJg5sQAdjzqtwoKBdI8AJRGShoZyINS5SB2jqXgeWr87wkG7i4I0CJRg27x30BX9tDH9/Z67nnoq6d/Oraa0HednQVjk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781627183; c=relaxed/simple; bh=uFa17sHyGg5Rg52MGCEAS5UltFrhzomoHLvvjdxU2U0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=VfN+L6qIDJPuo8586P9TDOGmlV725WLZChMfeQtJtSwyrHyv7S3EQxQrLVcTNkzrsuA/W6Y/UGLywVjqtHajeoB8yuCkmkGHUdjo5RfTxpNcYrSrEjyrNJPUV+3ZBrd9td6K8GiT2z8HPiFkEIDlwfnHGyUt33TZ0L1hqjF6/MA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=ycFN3zTe; 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="ycFN3zTe" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AD0E11F000E9; Tue, 16 Jun 2026 16:26:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1781627182; bh=viEMt1gOm/xrQKb42jKz5f/of67XMEaVPmyUNJpMXns=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=ycFN3zTeozLqrERT1wD+A3iws8LkOA8uTBVh0I2mEAbSLgphlTbX99Qm30OfLVjo+ dFuwqJk4dOfhSpxgjVlXQgpv8JOslPBydDH7iKF1r3p4+RIbcPb94POtxYJ4OXA8kk 4kzbNYAKve0EnATVSMg2iXZbVbe0Sq8xMHabnUcw= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Weiming Shi , Xiang Mei , Pablo Neira Ayuso , Sasha Levin Subject: [PATCH 6.12 100/261] netfilter: nf_log: validate MAC header was set before dumping it Date: Tue, 16 Jun 2026 20:28:58 +0530 Message-ID: <20260616145049.667194632@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260616145044.869532709@linuxfoundation.org> References: <20260616145044.869532709@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 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Xiang Mei [ Upstream commit a84b6fedbc97078788be78dbdd7517d143ad1a77 ] The fallback path of dump_mac_header() guards the MAC header access only with "skb->mac_header != skb->network_header", without checking skb_mac_header_was_set(). When the MAC header is unset, mac_header is 0xffff, so the test passes and skb_mac_header(skb) returns skb->head + 0xffff, ~64 KiB past the buffer; the loop then reads dev->hard_header_len bytes out of bounds into the kernel log. This is reachable via the netdev logger: nf_log_unknown_packet() calls dump_mac_header() unconditionally, and an skb sent through AF_PACKET with PACKET_QDISC_BYPASS reaches the egress hook with mac_header still unset (__dev_queue_xmit(), which would reset it, is bypassed). Add the skb_mac_header_was_set() check the ARPHRD_ETHER path already uses, and replace the open-coded MAC header length test with skb_mac_header_len(). Only skbs with an unset MAC header are affected; valid ones are dumped as before. BUG: KASAN: slab-out-of-bounds in dump_mac_header (net/netfilter/nf_log_syslog.c:831) Read of size 1 at addr ffff88800ea49d3f by task exploit/148 Call Trace: kasan_report (mm/kasan/report.c:595) dump_mac_header (net/netfilter/nf_log_syslog.c:831) nf_log_netdev_packet (net/netfilter/nf_log_syslog.c:938 net/netfilter/nf_log_syslog.c:963) nf_log_packet (net/netfilter/nf_log.c:260) nft_log_eval (net/netfilter/nft_log.c:60) nft_do_chain (net/netfilter/nf_tables_core.c:285) nft_do_chain_netdev (net/netfilter/nft_chain_filter.c:307) nf_hook_slow (net/netfilter/core.c:619) nf_hook_direct_egress (net/packet/af_packet.c:257) packet_xmit (net/packet/af_packet.c:280) packet_sendmsg (net/packet/af_packet.c:3114) __sys_sendto (net/socket.c:2265) Fixes: 7eb9282cd0ef ("netfilter: ipt_LOG/ip6t_LOG: add option to print decoded MAC header") Reported-by: Weiming Shi Assisted-by: Claude:claude-opus-4-8 Signed-off-by: Xiang Mei Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin --- net/netfilter/nf_log_syslog.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/netfilter/nf_log_syslog.c b/net/netfilter/nf_log_syslog.c index 58402226045e84..09b9152e9e5492 100644 --- a/net/netfilter/nf_log_syslog.c +++ b/net/netfilter/nf_log_syslog.c @@ -799,8 +799,8 @@ static void dump_mac_header(struct nf_log_buf *m, fallback: nf_log_buf_add(m, "MAC="); - if (dev->hard_header_len && - skb->mac_header != skb->network_header) { + if (dev->hard_header_len && skb_mac_header_was_set(skb) && + skb_mac_header_len(skb) != 0) { const unsigned char *p = skb_mac_header(skb); unsigned int i; -- 2.53.0