This is a note to let you know that I've just added the patch titled Revert "netfilter: conntrack: fix bug in for_each_sctp_chunk" to the 6.1-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: revert-netfilter-conntrack-fix-bug-in-for_each_sctp_.patch and it can be found in the queue-6.1 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit d9d9c2ee2bd9adc43afa74981da8f9976c87eef0 Author: Florian Westphal <fw@xxxxxxxxx> Date: Thu Jan 26 02:35:21 2023 +0100 Revert "netfilter: conntrack: fix bug in for_each_sctp_chunk" [ Upstream commit bd0e06f0def75ba26572a94e5350324474a55562 ] There is no bug. If sch->length == 0, this would result in an infinite loop, but first caller, do_basic_checks(), errors out in this case. After this change, packets with bogus zero-length chunks are no longer detected as invalid, so revert & add comment wrt. 0 length check. Fixes: 98ee00774525 ("netfilter: conntrack: fix bug in for_each_sctp_chunk") Signed-off-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/nf_conntrack_proto_sctp.c b/net/netfilter/nf_conntrack_proto_sctp.c index 444f02271b36a..490b11192e8aa 100644 --- a/net/netfilter/nf_conntrack_proto_sctp.c +++ b/net/netfilter/nf_conntrack_proto_sctp.c @@ -142,10 +142,11 @@ static void sctp_print_conntrack(struct seq_file *s, struct nf_conn *ct) } #endif +/* do_basic_checks ensures sch->length > 0, do not use before */ #define for_each_sctp_chunk(skb, sch, _sch, offset, dataoff, count) \ for ((offset) = (dataoff) + sizeof(struct sctphdr), (count) = 0; \ - ((sch) = skb_header_pointer((skb), (offset), sizeof(_sch), &(_sch))) && \ - (sch)->length; \ + (offset) < (skb)->len && \ + ((sch) = skb_header_pointer((skb), (offset), sizeof(_sch), &(_sch))); \ (offset) += (ntohs((sch)->length) + 3) & ~3, (count)++) /* Some validity checks to make sure the chunks are fine */