From 644c7e48cb59cfc6988ddc7bf3d3b1ba5fe7fa9d Mon Sep 17 00:00:00 2001 From: Jozsef Kadlecsik Date: Wed, 30 Mar 2016 11:34:35 +0200 Subject: [PATCH] netfilter: nf_conntrack_tcp: Fix stack out of bounds when parsing TCP options Baozeng Ding reported a KASAN stack out of bounds issue - it uncovered that the TCP option parsing routines in netfilter TCP connection tracking could read one byte out of the buffer of the TCP options. Therefore in the patch we check that the available data length is large enough to parse both TCP option code and size. Reported-by: Baozeng Ding Tested-by: Baozeng Ding Signed-off-by: Jozsef Kadlecsik Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_conntrack_proto_tcp.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/net/netfilter/nf_conntrack_proto_tcp.c b/net/netfilter/nf_conntrack_proto_tcp.c index 278f3b9356ef..7cc1d9c22a9f 100644 --- a/net/netfilter/nf_conntrack_proto_tcp.c +++ b/net/netfilter/nf_conntrack_proto_tcp.c @@ -410,6 +410,8 @@ static void tcp_options(const struct sk_buff *skb, length--; continue; default: + if (length < 2) + return; opsize=*ptr++; if (opsize < 2) /* "silly options" */ return; @@ -470,6 +472,8 @@ static void tcp_sack(const struct sk_buff *skb, unsigned int dataoff, length--; continue; default: + if (length < 2) + return; opsize = *ptr++; if (opsize < 2) /* "silly options" */ return; -- 2.20.1