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 84534443A91; Tue, 21 Jul 2026 22:31:48 +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=1784673109; cv=none; b=pcNcRzP57y3aN2qO4Z6cS9e5D678uxeWu84HEuEkO6TD5YWtRUCsqNizCA5BXdwpAN25ZDNYNdQQMzw9nYBfBUHDn4+SuNdLbpOBZMw5oZ4bz3hrwDwjzie1jPA8wwnkiWvcRZ8Cqz3AdT8+81BH2ri434fldxo8HhqhXJfRjhk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784673109; c=relaxed/simple; bh=T0ok0OM0HKwTKrd41+EcmFlxk4m3iQH1IgnuwuDAiRI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=oxKPCwiFynKCE6oBvALIbiq9aWhJEPBa3bmDPohCHycEqo4y9rBxpV9/zVDbLjMEB1cEAPG5E+LQp+DF+67/djyWgPPSo3phVTmgHS+NebH9DI5CuOeZa03HeM5/zLn0Kb/2GOV6u2ygYEkd0TlO+xdkWQQ7kQHMGg7ZFD7AaZ0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=BO1zkeuO; 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="BO1zkeuO" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E3E321F000E9; Tue, 21 Jul 2026 22:31:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784673108; bh=BdzFKPAnFJH2TJfDhOe8mpS3ZfifEF5IrlfgXMoxOjw=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=BO1zkeuORAs/7DWZXnT5C6Sirwv7BBmMPV+s8ErlKIIW4qLQvFOBBEz28wDvNonO6 fZk9Kt4dUlcrEd3UWq9qOX7iZVgbKl1EuJm+wi8B0ZXDwUT6aMmli8tWLA9sgIfn8x Dm6uoxyXsMwX9+wMiwW2p5B1oSgSgZkWW63BC38A= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Weiming Shi , Xiang Mei , Pablo Neira Ayuso , Alexander Martyniuk Subject: [PATCH 5.10 012/699] netfilter: nf_log: validate MAC header was set before dumping it Date: Tue, 21 Jul 2026 17:16:11 +0200 Message-ID: <20260721152355.959441686@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152355.667394603@linuxfoundation.org> References: <20260721152355.667394603@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 5.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Xiang Mei commit a84b6fedbc97078788be78dbdd7517d143ad1a77 upstream. 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: Alexander Martyniuk Signed-off-by: Greg Kroah-Hartman --- net/ipv4/netfilter/nf_log_ipv4.c | 4 ++-- net/ipv6/netfilter/nf_log_ipv6.c | 4 ++-- 2 files changed, 4 insertions(+), 4 deletions(-) --- a/net/ipv4/netfilter/nf_log_ipv4.c +++ b/net/ipv4/netfilter/nf_log_ipv4.c @@ -296,8 +296,8 @@ static void dump_ipv4_mac_header(struct 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; --- a/net/ipv6/netfilter/nf_log_ipv6.c +++ b/net/ipv6/netfilter/nf_log_ipv6.c @@ -309,8 +309,8 @@ static void dump_ipv6_mac_header(struct 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 len = dev->hard_header_len; unsigned int i;