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netfilter: nf_ct_tcp: fix incorrect handling of invalid TCP option

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Michael M. Builov reported that in the tcp_options and tcp_sack functions
of netfilter TCP conntrack the incorrect handling of invalid TCP option
with too big opsize may lead to read access beyond tcp-packet or buffer
allocated on stack (netfilter bugzilla #738). The fix is to stop parsing
the options at detecting the broken option.

Signed-off-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: Patrick McHardy <kaber@trash.net>
This commit is contained in:
Jozsef Kadlecsik 2011-08-30 15:45:10 +02:00 committed by Patrick McHardy
parent 4c6e420966
commit 4a5cc84ae7
1 changed files with 2 additions and 2 deletions
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4
net/netfilter/nf_conntrack_proto_tcp.c
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@ -409,7 +409,7 @@ static void tcp_options(const struct sk_buff *skb,
if (opsize < 2) /* "silly options" */
return;
if (opsize > length)
break; /* don't parse partial options */
return; /* don't parse partial options */
if (opcode == TCPOPT_SACK_PERM
&& opsize == TCPOLEN_SACK_PERM)
@ -469,7 +469,7 @@ static void tcp_sack(const struct sk_buff *skb, unsigned int dataoff,
if (opsize < 2) /* "silly options" */
return;
if (opsize > length)
break; /* don't parse partial options */
return; /* don't parse partial options */
if (opcode == TCPOPT_SACK
&& opsize >= (TCPOLEN_SACK_BASE