Bug #72801 [NEW]: apcu crashes (SIGSEGV) php/Apache on memory allocation failures
From: jaromird at microsoft dot com
Operating system: Mac OS X
PHP version: 7.0.9
Package: Reproducible crash
Bug Type: Bug
Bug description:apcu crashes (SIGSEGV) php/Apache on memory allocation failures
Description:
------------
Started seeing more frequent Apache crashes after upgrade to PHP 7.0 for
one of our applications which makes heavy use of apc cache. After
investigation, found a reproduction script to trigger segmentation fault
eventually.
Late apcu code inspection revealed that code doesn't check for memory
allocation failures on many places. Typical case for example: string
duplication fails in apcu_store(), code then inserts zval with NULL
value into cache, then apcu_fetch() crashes when dereferencing the
value.
I hope I've covered all necessary places in the patch, but surely would
suggest close review. So far only the case triggered by the below test
is really tested.
Test script:
---------------
<?php
/*
Might need tweaking to trigger the memory allocation failure
ini settings:
memory_limit = 4512M
apcu shared memory size default - 128M
*/
$f = str_repeat('c', 800 * 1024 * 1024 );
apcu_store('aaa', $f, 5);
$s = apcu_fetch('aaa');
echo ($s == $f) ? "same" : "different";
Expected result:
----------------
script running to completion, returning "same" if no memory problem,
"different" if memory allocation failure in apc_fetch()
Actual result:
--------------
Segmentation fault: 11
--
Edit bug report at https://bugs.php.net/bug.php?id=72801&edit=1
--
Try a snapshot (PHP 5.4): https://bugs.php.net/fix.php?id=72801&r=trysnapshot54
Try a snapshot (PHP 5.5): https://bugs.php.net/fix.php?id=72801&r=trysnapshot55
Try a snapshot (trunk): https://bugs.php.net/fix.php?id=72801&r=trysnapshottrunk
Fixed in SVN: https://bugs.php.net/fix.php?id=72801&r=fixed
Fixed in release: https://bugs.php.net/fix.php?id=72801&r=alreadyfixed
Need backtrace: https://bugs.php.net/fix.php?id=72801&r=needtrace
Need Reproduce Script: https://bugs.php.net/fix.php?id=72801&r=needscript
Try newer version: https://bugs.php.net/fix.php?id=72801&r=oldversion
Not developer issue: https://bugs.php.net/fix.php?id=72801&r=support
Expected behavior: https://bugs.php.net/fix.php?id=72801&r=notwrong
Not enough info: https://bugs.php.net/fix.php?id=72801&r=notenoughinfo
Submitted twice: https://bugs.php.net/fix.php?id=72801&r=submittedtwice
register_globals: https://bugs.php.net/fix.php?id=72801&r=globals
PHP 4 support discontinued: https://bugs.php.net/fix.php?id=72801&r=php4
Daylight Savings: https://bugs.php.net/fix.php?id=72801&r=dst
IIS Stability: https://bugs.php.net/fix.php?id=72801&r=isapi
Install GNU Sed: https://bugs.php.net/fix.php?id=72801&r=gnused
Floating point limitations: https://bugs.php.net/fix.php?id=72801&r=float
No Zend Extensions: https://bugs.php.net/fix.php?id=72801&r=nozend
MySQL Configuration Error: https://bugs.php.net/fix.php?id=72801&r=mysqlcfg
Thread (7 messages)
- jaromird at microsoft dot com