Bug #74240 [Opn->Csd]: deflate_add can allocate too much memory

Edit report at https://bugs.php.net/bug.php?id=74240&edit=1 ID: 74240 Updated by: bwoebi@php.net Reported by: matt at bonneau dot net Summary: deflate_add can allocate too much memory -Status: Open +Status: Closed Type: Bug Package: Zlib related Operating System: All PHP Version: master-Git-2017-03-13 (Git) Block user comment: N Private report: N New Comment: Automatic comment on behalf of matt@bonneau.net Revision: http://git.php.net/?p=php-src.git;a=commit;h=7fba8bda4c9e89c522e5d27a38489125e36b9904 Log: Fixed bug #74240 (deflate_add can allocate too much memory) Previous Comments: ------------------------------------------------------------------------ [2017-03-13 03:43:36] matt at bonneau dot net Description: ------------ deflate_add can grossly overestimate memory needed for the output buffer. This is more likely with highly compressable data. The allocations are roughly equal to the total bytes processed by deflate_add and can cause PHP to run out of memory. Test script: --------------- $deflator = deflate_init(ZLIB_ENCODING_RAW); $bytes = str_repeat("*", 65536); // if you use random bytes this usually can run forever // because they are not very compressable //$bytes = openssl_random_pseudo_bytes(65536); // this crashes after about 500 iterations if PHP is // configured for 64M for ($i = 0; $i < 100000; $i++) { echo "$i\n"; $output = deflate_add( $deflator, $bytes, ZLIB_SYNC_FLUSH ); } ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=74240&edit=1