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 <sploving1@gmail.com>
Tested-by: Baozeng Ding <sploving1@gmail.com>
Signed-off-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Jozsef Kadlecsik 2016-03-30 11:34:35 +02:00 committed by Pablo Neira Ayuso
parent ff76def3bd
commit 644c7e48cb

View file

@ -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;