This is a note to let you know that I've just added the patch titled netfilter: fix regression in looped (broad|multi)cast's MAC handling to the 5.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: netfilter-fix-regression-in-looped-broad-multi-cast-.patch and it can be found in the queue-5.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit f1abb5d2451fc063edf07c35f0b72671d978214b Author: Ignacy Gawędzki <ignacy.gawedzki@xxxxxxxxxxxxxxxxxxxxxxx> Date: Fri Dec 10 16:31:27 2021 +0100 netfilter: fix regression in looped (broad|multi)cast's MAC handling [ Upstream commit ebb966d3bdfed581ecccbb4a7432341baf7619b4 ] In commit 5648b5e1169f ("netfilter: nfnetlink_queue: fix OOB when mac header was cleared"), the test for non-empty MAC header introduced in commit 2c38de4c1f8da7 ("netfilter: fix looped (broad|multi)cast's MAC handling") has been replaced with a test for a set MAC header. This breaks the case when the MAC header has been reset (using skb_reset_mac_header), as is the case with looped-back multicast packets. As a result, the packets ending up in NFQUEUE get a bogus hwaddr interpreted from the first bytes of the IP header. This patch adds a test for a non-empty MAC header in addition to the test for a set MAC header. The same two tests are also implemented in nfnetlink_log.c, where the initial code of commit 2c38de4c1f8da7 ("netfilter: fix looped (broad|multi)cast's MAC handling") has not been touched, but where supposedly the same situation may happen. Fixes: 5648b5e1169f ("netfilter: nfnetlink_queue: fix OOB when mac header was cleared") Signed-off-by: Ignacy Gawędzki <ignacy.gawedzki@xxxxxxxxxxxxxxxxxxxxxxx> Reviewed-by: Florian Westphal <fw@xxxxxxxxx> Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/net/netfilter/nfnetlink_log.c b/net/netfilter/nfnetlink_log.c index 7ca2ca4bba055..b36af4741ad3c 100644 --- a/net/netfilter/nfnetlink_log.c +++ b/net/netfilter/nfnetlink_log.c @@ -557,7 +557,8 @@ __build_packet_message(struct nfnl_log_net *log, goto nla_put_failure; if (indev && skb->dev && - skb->mac_header != skb->network_header) { + skb_mac_header_was_set(skb) && + skb_mac_header_len(skb) != 0) { struct nfulnl_msg_packet_hw phw; int len; diff --git a/net/netfilter/nfnetlink_queue.c b/net/netfilter/nfnetlink_queue.c index a8cb562da3fea..ca21f8f4a47c1 100644 --- a/net/netfilter/nfnetlink_queue.c +++ b/net/netfilter/nfnetlink_queue.c @@ -562,7 +562,8 @@ nfqnl_build_packet_message(struct net *net, struct nfqnl_instance *queue, goto nla_put_failure; if (indev && entskb->dev && - skb_mac_header_was_set(entskb)) { + skb_mac_header_was_set(entskb) && + skb_mac_header_len(entskb) != 0) { struct nfqnl_msg_packet_hw phw; int len;