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Message-Id: <20230131133158.4052-3-pablo@netfilter.org>
Date: Tue, 31 Jan 2023 14:31:58 +0100
From: Pablo Neira Ayuso <pablo@...filter.org>
To: netfilter-devel@...r.kernel.org
Cc: davem@...emloft.net, netdev@...r.kernel.org, kuba@...nel.org,
pabeni@...hat.com, edumazet@...gle.com
Subject: [PATCH net 2/2] Revert "netfilter: conntrack: fix bug in for_each_sctp_chunk"
From: Florian Westphal <fw@...len.de>
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@...len.de>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
---
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 */
--
2.30.2
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