Re: [oops] in text matching

[Patrick McHardy <kaber@trash.net>]

Andrei Popa wrote:
> On Sat, 2007-11-10 at 13:57 +0100, Patrick McHardy wrote:
>> Andrei Popa wrote:
>>> The oops is reproducible by this script (yyy are some IP addresses):
>>>
>>> ...
>>> #$IPT -I INPUT -p tcp --dport 80 -m string --algo bm --string "$MyNick"
>>> -j DROP
>>
>> I could reproduce it with an empty string - is $MyNick defined?
> 
> it's not defined.
> 
>> Please try this patch.
> 
> it's ok now:
> 
> test ~ # iptables -I INPUT -p tcp --dport 80 -m string --algo bm
> --string "$MyNick" -j DROP
> iptables: Invalid argument


Thanks, thats whats expected. The patch is suboptimal though
since it should really allow patterns of length zero. Pablo,
the naive approach would be to ignore patlen == 0 in the
initialization path and return the current position in bm_find().
But I'm guessing there's a better way to handle this case,
could you look into this please? Thanks.

> 
>> plain text document attachment (x)
>> diff --git a/lib/ts_bm.c b/lib/ts_bm.c
>> index d90822c..5adb3ff 100644
>> --- a/lib/ts_bm.c
>> +++ b/lib/ts_bm.c
>> @@ -142,6 +142,9 @@ static struct ts_config *bm_init(const void *pattern, unsigned int len,
>>  	unsigned int prefix_tbl_len = len * sizeof(unsigned int);
>>  	size_t priv_size = sizeof(*bm) + len + prefix_tbl_len;
>>  
>> +	if (len == 0)
>> +		return ERR_PTR(-EINVAL);
>> +
>>  	conf = alloc_ts_config(priv_size, gfp_mask);
>>  	if (IS_ERR(conf))
>>  		return conf;
>