Bug #75797 [NEW]: Memory leak when using class_alias() in non-debug mode

From: aharvey Operating system: Linux x86-64 PHP version: 7.2Git-2018-01-10 (Git) Package: Scripting Engine problem Bug Type: Bug Bug description:Memory leak when using class_alias() in non-debug mode Description: ------------ When fast_shutdown in shutdown_executor() is non-zero (which is the normal case when PHP isn't compiled with --enable-debug), string keys added to the class table for aliased classes are not freed. This results in a leak of 32 bytes on 64 bit Linux for each call of class_alias(). This isn't an issue on master due to https://github.com/php/php-src/commit/8e01026b829f51d80d62648db9d81263454b2988, but it appears that all other 7.x branches are currently affected. That commit is tied up in a bunch of other GC refactoring, so simply cherry picking it to, say, PHP-7.2 results in other problems. (Not to mention the ABI break it would entail.) Test script: --------------- <?php class C {} class_alias(C::class, 'foo'); Expected result: ---------------- [aharvey@aharvey-mbp-linux master]$ valgrind --leak-check=full ./sapi/cli/php /tmp/test.php ==26338== Memcheck, a memory error detector ==26338== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al. ==26338== Using Valgrind-3.13.0 and LibVEX; rerun with -h for copyright info ==26338== Command: ./sapi/cli/php /tmp/test.php ==26338== ==26338== ==26338== HEAP SUMMARY: ==26338== in use at exit: 0 bytes in 0 blocks ==26338== total heap usage: 6,553 allocs, 6,553 frees, 1,267,251 bytes allocated ==26338== ==26338== All heap blocks were freed -- no leaks are possible ==26338== ==26338== For counts of detected and suppressed errors, rerun with: -v ==26338== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0) Actual result: -------------- [aharvey@aharvey-mbp-linux 7.2]$ valgrind --leak-check=full /opt/php/7.2/bin/php /tmp/test.php ==26331== Memcheck, a memory error detector ==26331== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al. ==26331== Using Valgrind-3.13.0 and LibVEX; rerun with -h for copyright info ==26331== Command: /opt/php/7.2/bin/php /tmp/test.php ==26331== ==26331== ==26331== HEAP SUMMARY: ==26331== in use at exit: 1,158 bytes in 22 blocks ==26331== total heap usage: 27,180 allocs, 27,158 frees, 3,329,121 bytes allocated ==26331== ==26331== 32 bytes in 1 blocks are definitely lost in loss record 10 of 22 ==26331== at 0x4C2CEDF: malloc (vg_replace_malloc.c:299) ==26331== by 0xA1E804: __zend_malloc (zend_alloc.c:2829) ==26331== by 0xA75467: zend_string_alloc (zend_string.h:134) ==26331== by 0xA75467: zend_register_class_alias_ex (zend_API.c:2782) ==26331== by 0xAA0B7F: zif_class_alias (zend_builtin_functions.c:1530) ==26331== by 0xC11330: ZEND_DO_ICALL_SPEC_RETVAL_UNUSED_HANDLER (zend_vm_execute.h:573) ==26331== by 0xC11330: execute_ex (zend_vm_execute.h:59731) ==26331== by 0xC284AA: zend_execute (zend_vm_execute.h:63760) ==26331== by 0xA671A4: zend_execute_scripts (zend.c:1496) ==26331== by 0x9AC153: php_execute_script (main.c:2590) ==26331== by 0xC2BE18: do_cli (php_cli.c:1011) ==26331== by 0xC2D1DF: main (php_cli.c:1404) ==26331== ==26331== LEAK SUMMARY: ==26331== definitely lost: 32 bytes in 1 blocks ==26331== indirectly lost: 0 bytes in 0 blocks ==26331== possibly lost: 0 bytes in 0 blocks ==26331== still reachable: 1,126 bytes in 21 blocks ==26331== suppressed: 0 bytes in 0 blocks ==26331== Reachable blocks (those to which a pointer was found) are not shown. ==26331== To see them, rerun with: --leak-check=full --show-leak-kinds=all ==26331== ==26331== For counts of detected and suppressed errors, rerun with: -v ==26331== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0) -- Edit bug report at https://bugs.php.net/bug.php?id=75797&edit=1 -- Try a snapshot (PHP 5.4): https://bugs.php.net/fix.php?id=75797&r=trysnapshot54 Try a snapshot (PHP 5.5): https://bugs.php.net/fix.php?id=75797&r=trysnapshot55 Try a snapshot (trunk): https://bugs.php.net/fix.php?id=75797&r=trysnapshottrunk Fixed in SVN: https://bugs.php.net/fix.php?id=75797&r=fixed Fixed in release: https://bugs.php.net/fix.php?id=75797&r=alreadyfixed Need backtrace: https://bugs.php.net/fix.php?id=75797&r=needtrace Need Reproduce Script: https://bugs.php.net/fix.php?id=75797&r=needscript Try newer version: https://bugs.php.net/fix.php?id=75797&r=oldversion Not developer issue: https://bugs.php.net/fix.php?id=75797&r=support Expected behavior: https://bugs.php.net/fix.php?id=75797&r=notwrong Not enough info: https://bugs.php.net/fix.php?id=75797&r=notenoughinfo Submitted twice: https://bugs.php.net/fix.php?id=75797&r=submittedtwice register_globals: https://bugs.php.net/fix.php?id=75797&r=globals PHP 4 support discontinued: https://bugs.php.net/fix.php?id=75797&r=php4 Daylight Savings: https://bugs.php.net/fix.php?id=75797&r=dst IIS Stability: https://bugs.php.net/fix.php?id=75797&r=isapi Install GNU Sed: https://bugs.php.net/fix.php?id=75797&r=gnused Floating point limitations: https://bugs.php.net/fix.php?id=75797&r=float No Zend Extensions: https://bugs.php.net/fix.php?id=75797&r=nozend MySQL Configuration Error: https://bugs.php.net/fix.php?id=75797&r=mysqlcfg