Bug #77289 [NEW]: php-fpm workers are segfaulting intermittently

From: Date: Wed, 12 Dec 2018 16:10:27 +0000
Subject: Bug #77289 [NEW]: php-fpm workers are segfaulting intermittently
Groups: php.bugs 
Request: Send a blank email to php-bugs+get-218423@lists.php.net to get a copy of this message 
From:             bugs dot php dot net at mundpropaganda dot net
Operating system: Linux 4.14.82
PHP version:      7.3.0
Package:          opcache
Bug Type:         Bug
Bug description:php-fpm workers are segfaulting intermittently

Description:
------------
Hey there,

after upgrading from PHP 7.2.13 to to 7.3.0 I noticed php-fpm workers
frequently crashing while serving WordPress. Downgrading back to 7.2.13
fixed all issues.

The crashes seem to happen after I empty the cache of the wp-supercache
plugin and access a previously uncached page of the website, although
they are rather intermittent; sometimes occurring immediately, sometimes
I have to click around a bit for it to trigger and other times it works
just fine.

I was able to dump the core of a worker process when it happened:

Core was generated by php-fpm: pool amm-php73.
Program terminated with signal SIGSEGV, Segmentation fault.
#0  zend_mm_alloc_small (bin_num=4, size=40, heap=0x7f9fea600040)
    at /home/krist/tmp/php-7.3.0/Zend/zend_alloc.c:1287
#1  zend_mm_alloc_heap (size=40, heap=0x7f9fea600040)
    at /home/krist/tmp/php-7.3.0/Zend/zend_alloc.c:1358
#2  _emalloc (size=size@entry=40) at
/home/krist/tmp/php-7.3.0/Zend/zend_alloc.c:2498
#3  0x000055e2dc8d84aa in zend_string_alloc (persistent=0, len=8)
    at /home/krist/tmp/php-7.3.0/Zend/zend_string.h:155
#4  zend_string_init (persistent=0, len=8, str=<optimized out>)
    at /home/krist/tmp/php-7.3.0/Zend/zend_string.h:155
#5  lex_scan (zendlval=zendlval@entry=0x7ffcbae3dbc0,
elem=0x7ffcbae3dc48)
    at Zend/zend_language_scanner.l:2760
#6  0x000055e2dc8ebe4a in zendlex (elem=elem@entry=0x7ffcbae3dc48)
    at /home/krist/tmp/php-7.3.0/Zend/zend_compile.c:1693
#7  0x000055e2dc8d172e in zendparse () at
/home/krist/tmp/php-7.3.0/Zend/zend_language_parser.c:4211
#8  0x000055e2dc8d3c2a in zend_compile (type=type@entry=2) at
Zend/zend_language_scanner.l:586
#9  0x000055e2dc8d540a in compile_file (file_handle=0x7ffcbae3ebc0,
type=2)
    at Zend/zend_language_scanner.l:636
#10 0x000055e2dc7ada72 in phar_compile_file (file_handle=0x7ffcbae3ebc0,
type=2)
    at /home/krist/tmp/php-7.3.0/ext/phar/phar.c:3344
#11 0x00007f9fea8a106c in opcache_compile_file
(file_handle=0x7ffcbae3ebc0, type=2,
    op_array_p=0x7ffcbae3eaa8, key=<optimized out>)
    at /home/krist/tmp/php-7.3.0/ext/opcache/ZendAccelerator.c:1750
#12 0x00007f9fea8a332f in persistent_compile_file (type=2,
file_handle=0x7ffcbae3ebc0)
    at /home/krist/tmp/php-7.3.0/ext/opcache/ZendAccelerator.c:2095
#13 persistent_compile_file (file_handle=0x7ffcbae3ebc0, type=2)
    at /home/krist/tmp/php-7.3.0/ext/opcache/ZendAccelerator.c:1889
#14 0x000055e2dc8d54b2 in compile_filename (type=type@entry=2,
filename=filename@entry=0x7f9fea61da40)
    at Zend/zend_language_scanner.l:661
#15 0x000055e2dc94dc65 in zend_include_or_eval
(inc_filename=inc_filename@entry=0x7f9fea61da40,
    type=2) at /home/krist/tmp/php-7.3.0/Zend/zend_execute.c:3182
#16 0x000055e2dc983d10 in ZEND_INCLUDE_OR_EVAL_SPEC_TMPVAR_HANDLER ()
    at /home/krist/tmp/php-7.3.0/Zend/zend_vm_execute.h:12697
#17 0x000055e2dc989f0f in execute_ex (ex=0x861e00)
    at /home/krist/tmp/php-7.3.0/Zend/zend_vm_execute.h:56832
#18 0x000055e2dc990702 in zend_execute
(op_array=op_array@entry=0x7f9fe339f958, return_value=0x0,
    return_value@entry=0x7f9fea61d9a0) at
/home/krist/tmp/php-7.3.0/Zend/zend_vm_execute.h:60834
#19 0x000055e2dc90ad83 in zend_execute_scripts (type=type@entry=8,
retval=0x7f9fea61d9a0,
    retval@entry=0x0, file_count=file_count@entry=3) at
/home/krist/tmp/php-7.3.0/Zend/zend.c:1568
#20 0x000055e2dc8ac228 in php_execute_script (primary_file=<optimized
out>)
    at /home/krist/tmp/php-7.3.0/main/main.c:2630
#21 0x000055e2dc69f290 in main (argc=<optimized out>, argv=<optimized
out>)
    at /home/krist/tmp/php-7.3.0/sapi/fpm/fpm/fpm_main.c:1950

Let me know if there's anything I might do or provide to help tracing
this bug.

– Christian


-- 
Edit bug report at https://bugs.php.net/bug.php?id=77289&edit=1
-- 
Try a snapshot (PHP 5.4):   https://bugs.php.net/fix.php?id=77289&r=trysnapshot54
Try a snapshot (PHP 5.5):   https://bugs.php.net/fix.php?id=77289&r=trysnapshot55
Try a snapshot (trunk):     https://bugs.php.net/fix.php?id=77289&r=trysnapshottrunk
Fixed in SVN:               https://bugs.php.net/fix.php?id=77289&r=fixed
Fixed in release:           https://bugs.php.net/fix.php?id=77289&r=alreadyfixed
Need backtrace:             https://bugs.php.net/fix.php?id=77289&r=needtrace
Need Reproduce Script:      https://bugs.php.net/fix.php?id=77289&r=needscript
Try newer version:          https://bugs.php.net/fix.php?id=77289&r=oldversion
Not developer issue:        https://bugs.php.net/fix.php?id=77289&r=support
Expected behavior:          https://bugs.php.net/fix.php?id=77289&r=notwrong
Not enough info:            https://bugs.php.net/fix.php?id=77289&r=notenoughinfo
Submitted twice:            https://bugs.php.net/fix.php?id=77289&r=submittedtwice
register_globals:           https://bugs.php.net/fix.php?id=77289&r=globals
PHP 4 support discontinued: https://bugs.php.net/fix.php?id=77289&r=php4
Daylight Savings:           https://bugs.php.net/fix.php?id=77289&r=dst
IIS Stability:              https://bugs.php.net/fix.php?id=77289&r=isapi
Install GNU Sed:            https://bugs.php.net/fix.php?id=77289&r=gnused
Floating point limitations: https://bugs.php.net/fix.php?id=77289&r=float
No Zend Extensions:         https://bugs.php.net/fix.php?id=77289&r=nozend
MySQL Configuration Error:  https://bugs.php.net/fix.php?id=77289&r=mysqlcfg

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