Req #60655 [Opn]: add max_input_vars for json/serialize

Edit report at https://bugs.php.net/bug.php?id=60655&edit=1 ID: 60655 Updated by: laruence@php.net Reported by: laruence@php.net Summary: add max_input_vars for json/serialize Status: Open Type: Feature/Change Request Package: *General Issues PHP Version: 5.3.9RC4 Block user comment: N Private report: N New Comment: sesser, yes, you are right, a constant can not fix this problem, only make it more diffcult to find the special keys.. Previous Comments: ------------------------------------------------------------------------ [2012-01-05 14:52:32] sesser@php.net laruence: nothing against you, but fixing the hash table thing is not a simple easy fix. It must be done by someone who understands the mathematical problem of hash collisions and who understands the impact of making changes to a hash function. Just changing some constants in the algorithm will not improve the situation. The opposite can be the case. By changing some constants it could be possible to destroy the distribution of collisions and suddenly some values collide more often than others. So please do not try to fix a problem that must be solved by someone with the mathematical background knowledge. ------------------------------------------------------------------------ [2012-01-05 14:48:14] sesser@php.net BTW a simple approach to cause 65536 alpha numerical collisions would use most probably less than 2MB of POST payload. And this is the NOT mathematically optimized version. ------------------------------------------------------------------------ [2012-01-05 14:47:21] laruence@php.net sesser, I am not good at algorithm, so if you can help me, I will appreciate. just a guess, what about change the zend_hash_func, add some new seed like: register ulong hash = 5381 + nKeyLength; thanks ------------------------------------------------------------------------ [2012-01-05 14:44:32] sesser@php.net It is not "a theory", The whole disclosure from n-runs was about colliding the DJB hash function with alpha numerical keys. ------------------------------------------------------------------------ [2012-01-05 14:14:08] laruence@php.net <laruence> I got you point, and agree in theory, yes, the string hash value could be the same, does anyone have a method to compute it in real? <nikic> yes <laruence> I really doubt that if we can find so many string keys with the same hash value to be able launch a attach, and won't reach the max post size ------------------------------------------------------------------------ The remainder of the comments for this report are too long. To view the rest of the comments, please view the bug report online at https://bugs.php.net/bug.php?id=60655 -- Edit this bug report at https://bugs.php.net/bug.php?id=60655&edit=1