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netfilter: nf_ct_sip: don't drop packets with offsets pointing outside the packet

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Some Cisco phones create huge messages that are spread over multiple packets.
After calculating the offset of the SIP body, it is validated to be within
the packet and the packet is dropped otherwise. This breaks operation of
these phones. Since connection tracking is supposed to be passive, just let
those packets pass unmodified and untracked.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Patrick McHardy 2013-04-05 08:13:30 +00:00 committed by Pablo Neira Ayuso
parent 53f63189b1
commit 3a7b21eaf4
1 changed files with 2 additions and 4 deletions
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6
net/netfilter/nf_conntrack_sip.c
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@ -1593,10 +1593,8 @@ static int sip_help_tcp(struct sk_buff *skb, unsigned int protoff,
end += strlen("\r\n\r\n") + clen;
msglen = origlen = end - dptr;
if (msglen > datalen) {
nf_ct_helper_log(skb, ct, "incomplete/bad SIP message");
return NF_DROP;
}
if (msglen > datalen)
return NF_ACCEPT;
ret = process_sip_msg(skb, ct, protoff, dataoff,
&dptr, &msglen);