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 3770C4E7802; Tue, 13 Oct 2026 11:59:37 +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=1791892779; cv=none; b=eoMGbvht2TRMD/CSdMo711/SCRBoFGErF16jfpsuPK0epa2VycfFggLkO/3Lq4cIGUKU3s2hQG2VlOffCZoImfPcyOjdb/QhKGwe4ik3+DtdSQ5WhBReY4qgJYptutigU/UTE8ELB3wXpjnbES0RUnNefKCXgL79hQu1B0jmYYM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791892779; c=relaxed/simple; bh=Yvaaq/bxyfPqgHztFsYHqk/BogDshk2dKH9su6ugOIw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=eMkHz78w4Mf9MyNF4dv41US0BJmCcstwHw5qq86vtpuySGAd9CMGqqj1TN8SdozT8aw2uAbZFysewcH7TxGHN+DTtASPikKLxkkoXtSkCxoNmQ9dTUMMk9DFt0T+KvfgoxNN9g1WFKzvVQwH3olDqI1bdAe6NRcBkLb8FWQ5hWE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=u38tNkyP; 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="u38tNkyP" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3E67D1F000FF; Tue, 13 Oct 2026 11:59:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1791892777; bh=zJKslhmRBvtnuC/0Pzm4y+WPjGNEcEWB2heFcqwmchg=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=u38tNkyPh/f2sU0KcpFv1F2S/229KLefjBHoTwUm2KHPwK9ti0DPYd6H7m27TbxXd 2dWv4tkZrnge0P+tJYvfq8tdJSMC7Le2UXz4xXVgs4MMDIm9FPzlfljiUYhzxeezw6 vAIHIiUUCsynCeQ0BWbnPbIPUtAQpwchKm9BVMo8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+4cc63fcfb3845e149969@syzkaller.appspotmail.com, Fernando Fernandez Mancera , Ilya Maximets , Jakub Kicinski , Sasha Levin Subject: [PATCH 7.2 271/281] net: openvswitch: validate transport header presence in set_ipv6_addr Date: Tue, 13 Oct 2026 13:39:47 +0200 Message-ID: <20261013112901.715503849@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261013112855.045212108@linuxfoundation.org> References: <20261013112855.045212108@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 7.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Fernando Fernandez Mancera [ Upstream commit 3c6a4b11330fe424557538a98fca9f0a4c5bf313 ] When executing IPv6 address rewrite actions on IPv6 fragments, set_ipv6_addr() calls update_ipv6_checksum(). If parse_ipv6hdr() processes a non-first IPv6 fragment, it sets key->ip.proto to NEXTHDR_FRAGMENT and returns early without calling skb_set_transport_header(). update_ipv6_checksum() unconditionally evaluates skb_transport_offset() on entry before checking l4_proto. Because skb->transport_header is uninitialized, this triggers a warning under CONFIG_DEBUG_NET=y although it is completely harmless. Fix this by returning early in update_ipv6_checksum() if l4_proto is NEXTHDR_FRAGMENT. This avoids reading the uninitialized transport offset for fragments while preserving the debug warning for any other protocol where the transport header is unexpectedly missing. See the syzbot trace: !skb_transport_header_was_set(skb) WARNING: ./include/linux/skbuff.h:3075 at skb_transport_header include/linux/skbuff.h:3075 [inline], CPU#1: syz-executor463/5635 WARNING: ./include/linux/skbuff.h:3075 at skb_transport_offset include/linux/skbuff.h:3250 [inline], CPU#1: syz-executor463/5635 WARNING: ./include/linux/skbuff.h:3075 at update_ipv6_checksum net/openvswitch/actions.c:361 [inline], CPU#1: syz-executor463/5635 WARNING: ./include/linux/skbuff.h:3075 at set_ipv6_addr+0x462/0x660 net/openvswitch/actions.c:399, CPU#1: syz-executor463/5635 [...] RIP: 0010:skb_transport_header include/linux/skbuff.h:3075 [inline] RIP: 0010:skb_transport_offset include/linux/skbuff.h:3250 [inline] RIP: 0010:update_ipv6_checksum net/openvswitch/actions.c:361 [inline] RIP: 0010:set_ipv6_addr+0x462/0x660 net/openvswitch/actions.c:399 [...] Call Trace: set_ipv6 net/openvswitch/actions.c:531 [inline] do_execute_actions+0x557e/0x8600 net/openvswitch/actions.c:1366 ovs_execute_actions+0xde/0x520 net/openvswitch/actions.c:1592 ovs_packet_cmd_execute+0xb4f/0xf10 net/openvswitch/datapath.c:705 genl_family_rcv_msg_doit+0x233/0x340 net/netlink/genetlink.c:1114 genl_rcv_msg+0x614/0x7a0 net/netlink/genetlink.c:1209 netlink_rcv_skb+0x226/0x4a0 net/netlink/af_netlink.c:2572 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218 netlink_unicast+0x7bd/0x940 net/netlink/af_netlink.c:1361 netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1916 sock_sendmsg_nosec+0x14e/0x190 net/socket.c:800 Reported-by: syzbot+4cc63fcfb3845e149969@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=4cc63fcfb3845e149969 Fixes: 3fdbd1ce11e5 ("openvswitch: add ipv6 'set' action") Signed-off-by: Fernando Fernandez Mancera Reviewed-by: Ilya Maximets Link: https://patch.msgid.link/20261008104135.4722-1-fmancera@suse.de Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/openvswitch/actions.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c index dc5ff859f1145..27152bca8a8ce 100644 --- a/net/openvswitch/actions.c +++ b/net/openvswitch/actions.c @@ -358,7 +358,12 @@ static void set_ip_addr(struct sk_buff *skb, struct iphdr *nh, static void update_ipv6_checksum(struct sk_buff *skb, u8 l4_proto, __be32 addr[4], const __be32 new_addr[4]) { - int transport_len = skb->len - skb_transport_offset(skb); + int transport_len; + + if (l4_proto == NEXTHDR_FRAGMENT) + return; + + transport_len = skb->len - skb_transport_offset(skb); if (l4_proto == NEXTHDR_TCP) { if (likely(transport_len >= sizeof(struct tcphdr))) -- 2.53.0