Bug #79548 [Ver]: Segfault when using static inline variable inside a trait

Edit report at https://bugs.php.net/bug.php?id=79548&edit=1 ID: 79548 Updated by: nikic@php.net Reported by: luca at sungazer dot io Summary: Segfault when using static inline variable inside a trait Status: Verified Type: Bug Package: opcache Operating System: Linux PHP Version: 7.4.5 Block user comment: N Private report: N New Comment: The trait usage here was a red herring, this is sufficient: class A { public function test() { static $foo; } } class B extends A {} Previous Comments: ------------------------------------------------------------------------ [2020-05-04 14:08:56] nikic@php.net Minimal: // preload.php trait T { public function test() { static $foo; } } class A { use T; } class B extends A {} // script.php (new B)->test(); Trace: #0 0x0000555555da20e6 in _zend_is_inconsistent (ht=0x0, file=0x55555664f608 "/home/nikic/php-7.4/Zend/zend_hash.c", line=2045) at /home/nikic/php-7.4/Zend/zend_hash.c:54 #1 0x0000555555da8abb in zend_array_dup (source=0x0) at /home/nikic/php-7.4/Zend/zend_hash.c:2045 #2 0x0000555555e6131d in ZEND_BIND_STATIC_SPEC_CV_UNUSED_HANDLER () at /home/nikic/php-7.4/Zend/zend_vm_execute.h:46850 #3 0x0000555555e6c0a0 in execute_ex (ex=0x7fffeb613020) at /home/nikic/php-7.4/Zend/zend_vm_execute.h:57622 #4 0x0000555555e6c594 in zend_execute (op_array=0x7fffeb67a300, return_value=0x7fffffffc550) at /home/nikic/php-7.4/Zend/zend_vm_execute.h:57922 ------------------------------------------------------------------------ [2020-04-30 15:33:49] luca at sungazer dot io Description: ------------ Configuration: * Custom image built from https://hub.docker.com/_/php * Nginx + PHP-FPM * Symfony 5.0.8 * PHP 7.4.5 * Preloading enabled (preload file generated by Symfony) Description: When using the Symfony Cache component, php-fpm was terminating with SIGSEGV whenever I wanted to call the cache get() method. This happened only when preloading was enabled. After further investigation, I saw that the segmentation fault happens at this line of Symfony's ContractsTrait https://github.com/symfony/symfony/blob/master/src/Symfony/Component/Cache/Traits/ContractsTrait.php#L58 i.e. at the declaration of a static variable inside a private method of a Trait. A similar issue was reported on Symfony's issue list as well: https://github.com/symfony/symfony/issues/36328 As a workaround, I tried moving the declaration outside the function (i.e. at trait level private static $setMetadata) and then code started working as intended. Disabling preloading also fixes the issue. Test script: --------------- Please see the following repository: https://github.com/luca-nardelli/symfony-cache-segfault-reproducer/tree/master ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=79548&edit=1