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SubjectRe: [PATCH] netfilter: nf_conntrack_sip: CSeq 0 is a valid CSeq
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Le 04/07/2016 à 07:48, Liping Zhang a écrit :
> 2016-07-01 17:48 GMT+08:00 Christophe Leroy <christophe.leroy@c-s.fr>:
>> Do not drop packet when CSeq is 0 as 0 is also a valid value for CSeq.
>>
>> --- a/net/netfilter/nf_conntrack_sip.c
>> +++ b/net/netfilter/nf_conntrack_sip.c
>> @@ -1368,6 +1368,7 @@ static int process_sip_response(struct sk_buff *skb, unsigned int protoff,
>> struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
>> unsigned int matchoff, matchlen, matchend;
>> unsigned int code, cseq, i;
>> + char buf[21];
>>
>> if (*datalen < strlen("SIP/2.0 200"))
>> return NF_ACCEPT;
>> @@ -1382,8 +1383,13 @@ static int process_sip_response(struct sk_buff *skb, unsigned int protoff,
>> nf_ct_helper_log(skb, ct, "cannot parse cseq");
>> return NF_DROP;
>> }
>> - cseq = simple_strtoul(*dptr + matchoff, NULL, 10);
>> - if (!cseq) {
>
> I think there is no need to convert simple_strtoul to kstrtouint, add
> a further check seems better?
> Like this:
> - if (!cseq) {
> + if (!cseq && *(*dptr + matchoff) != '0') {
>

And what about an invalid CSeq that would look like CSeq: 0abzk852 ?
Should we check it is 0 + space instead ?

>> + if (matchlen > sizeof(buf) - 1) {
>> + nf_ct_helper_log(skb, ct, "cannot parse cseq (too big)");
>> + return NF_DROP;
>> + }
>> + memcpy(buf, *dptr + matchoff, matchlen);
>> + buf[matchlen] = 0;
>> + if (kstrtouint(buf, 10, &cseq)) {
>> nf_ct_helper_log(skb, ct, "cannot get cseq");
>> return NF_DROP;
>> }

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