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From Jim Jagielski <...@jaguNET.com>
Subject Re: Fixing Ranges
Date Thu, 25 Aug 2011 11:40:36 GMT
Tested and this does appear to both address the DoS as well as
reduce memory usage for "excessive" range requests…

+1 for adding this no matter what.

On Aug 24, 2011, at 7:38 PM, Stefan Fritsch wrote:

> On Thursday 25 August 2011, Greg Ames wrote:
>> On Wed, Aug 24, 2011 at 5:16 PM, Stefan Fritsch <sf@sfritsch.de> 
> wrote:
>>> I have another idea: Instead of using apr_brigade_partition write
>>> a new function ap_brigade_copy_part that leaves the original
>>> brigade untouched. It would copy the necessary buckets to a new
>>> brigade and then split the first and last of those copied
>>> buckets as necessary and destroy the excess buckets. AFAICS,
>>> this would reduce the quadratic growth into linear. Do you think
>>> that would solve our problems?
>> 
>> How does apr_brigade_partition contribute to quadratic growth? 
>> Does the original brigade end up with a lot of one byte buckets?
> 
> Yes, it splits the buckets in the original brigade, creating up to two 
> new buckets for every range. These split one-byte buckets are then 
> copied again for each of the subsequent ranges.
> 
> The attached PoC patch does not change the original brigade and seems 
> to fix the DoS for me. It needs some more work and some review for 
> integer overflows, though. (apr_brigade_partition does some 
> interesting things there).
> <range-linear.diff>


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