Bug #52327 [Asn->Csd]: base64_decode() improper handling of leading padding.

Edit report at http://bugs.php.net/bug.php?id=52327&edit=1 ID: 52327 Updated by: iliaa@php.net Reported by: yuri-sevatz at hotmail dot com Summary: base64_decode() improper handling of leading padding. -Status: Assigned +Status: Closed Type: Bug Package: *Compression related Operating System: ALL PHP Version: 5.3.2 Assigned To: iliaa Block user comment: N Private report: N New Comment: This bug has been fixed in SVN. Snapshots of the sources are packaged every three hours; this change will be in the next snapshot. You can grab the snapshot at http://snaps.php.net/. Thank you for the report, and for helping us make PHP better. Fixed when strict mode is being used. Previous Comments: ------------------------------------------------------------------------ [2010-11-26 21:59:15] iliaa@php.net Automatic comment from SVN on behalf of iliaa Revision: http://svn.php.net/viewvc/?view=revision&amp;revision=305779 Log: Fixed bug #52327 (base64_decode() improper handling of leading padding in strict mode) ------------------------------------------------------------------------ [2010-07-13 11:12:17] yuri-sevatz at hotmail dot com Description: ------------ According to the MIME standard that we're following, this isn't supposed to work when strict mode is enabled. Equal-signs are strictly reserved for padding characters at the _end_ of a base64 MIME string. Leading '=' signs are allowed in each block of 4 bytes because the condition that checks for invalid placement of the '=' signs only checks if (i % 4) == 1, Whereas it should check if (i % 4) is 0 or 1. You should be able to change the circumstances for a valid '=' placement, as follows, to conform to the standard: // to see if bit position 2 is set (for all values of i = n*4+2 and i = n*4+3) if (i & 2) // means that the '=' is in a valid location I would also suggest *carefully* looking over the block at the end of the base64_decode() function... as it seems that if (ch == base64_pad) after ch is ALWAYS set to '\0' is an impossible scenario. Test script: --------------- <?php echo base64_decode('=VGhl=ICc9=JyBz=eW1i=b2xz=IGFy=ZW4n=dCBh=bGxv=d2Vk=IHdo=ZXJl=IGkg=cHV0=IHRo=ZW0g=by5P'); ?> Expected result: ---------------- should return FALSE/NULL/Errornous value Actual result: -------------- echos: The '=' symbols aren't allowed where i put them o.O ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/bug.php?id=52327&edit=1