From bd0e06f0def75ba26572a94e5350324474a55562 Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Thu, 26 Jan 2023 02:35:21 +0100 Subject: [PATCH] Revert "netfilter: conntrack: fix bug in for_each_sctp_chunk" 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 Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_conntrack_proto_sctp.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/net/netfilter/nf_conntrack_proto_sctp.c b/net/netfilter/nf_conntrack_proto_sctp.c index 945dd40e7077..011d414038ea 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 */