netdev - Re: [PATCH] netfilter: nf_conntrack

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Message-ID: <CAML_gOeiqhdtV7Q0X8PWCoj1VDsTcWUhsCYcmLhdTigoaY=3tQ@mail.gmail.com>
Date:	Mon, 4 Jul 2016 19:43:45 +0800
From:	Liping Zhang <zlpnobody@...il.com>
To:	Christophe Leroy <christophe.leroy@....fr>
Cc:	Pablo Neira Ayuso <pablo@...filter.org>,
	Patrick McHardy <kaber@...sh.net>,
	Jozsef Kadlecsik <kadlec@...ckhole.kfki.hu>,
	"David S. Miller" <davem@...emloft.net>,
	netfilter-devel@...r.kernel.org, coreteam@...filter.org,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] netfilter: nf_conntrack_sip: CSeq 0 is a valid CSeq

2016-07-04 14:14 GMT+08:00 Christophe Leroy <christophe.leroy@....fr>:
>> 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 ?

In this case, i.e. some stupid sip clients set CSeq to "0abzk852",
your patch will also fail to detect this "error".

Because for "Cseq", int (*match_len)(...) point to digits_len(see
struct sip_header ct_sip_hdrs definition).
So in this case match_len will just be setted to ONE (not
sizeof("0abzk852")-1), then cseq will be parsed
as 0 by  kstrtouint, not as an error.