[php-maint] Bug#817917: Segfault in zval_scan_black

[Dejan SANADER]

Package: php5
Version: 5.6.17+dfsg-0+deb8u1

Hello,

I'm experiencing a systematic segfault on a peculiar page of a PHP app.

I've obtained the following backtrace.

I suppose more useful input might be needed, please advize me in that 
case on what must be retrieved and how.

Regards.


Program received signal SIGSEGV, Segmentation fault.
0x00007ffff36acb4e in zval_scan_black (pz=<optimized out>) at 
/build/php5-5.6.17+dfsg/Zend/zend_gc.c:313
313 /build/php5-5.6.17+dfsg/Zend/zend_gc.c: No such file or directory.
#0  0x00007ffff36acb4e in zval_scan_black (pz=<optimized out>) at 
/build/php5-5.6.17+dfsg/Zend/zend_gc.c:313
#1  0x00007ffff36acee4 in zobj_scan_black (pz=<optimized out>, 
pz at entry=0x7fffffe36740, obj=<optimized out>)
     at /build/php5-5.6.17+dfsg/Zend/zend_gc.c:347
#2  0x00007ffff36ada7e in zobj_scan (pz=0x7fffffe36740) at 
/build/php5-5.6.17+dfsg/Zend/zend_gc.c:580
#3  gc_scan_roots () at /build/php5-5.6.17+dfsg/Zend/zend_gc.c:620
#4  gc_collect_cycles () at /build/php5-5.6.17+dfsg/Zend/zend_gc.c:791
#5  0x00007ffff36adb8f in gc_zobj_possible_root (zv=0x555555e5c8b0) at 
/build/php5-5.6.17+dfsg/Zend/zend_gc.c:216
#6  0x00007ffff373b01d in gc_zval_check_possible_root (z=<optimized out>)
     at /build/php5-5.6.17+dfsg/Zend/zend_gc.h:183
#7  i_zval_ptr_dtor (zval_ptr=<optimized out>) at 
/build/php5-5.6.17+dfsg/Zend/zend_execute.h:86
#8  zend_vm_stack_clear_multiple (nested=<optimized out>) at 
/build/php5-5.6.17+dfsg/Zend/zend_execute.h:308
#9  zend_do_fcall_common_helper_SPEC (execute_data=0x5555585a1f48)
     at /build/php5-5.6.17+dfsg/Zend/zend_vm_execute.h:650
#10 0x00007ffff36c9dc0 in execute_ex (execute_data=0x5555585a1f48)
     at /build/php5-5.6.17+dfsg/Zend/zend_vm_execute.h:363
#11 0x00007ffff367b5b8 in dtrace_execute_ex (execute_data=0x5555585a1f48)
     at /build/php5-5.6.17+dfsg/Zend/zend_dtrace.c:73
[...]
#15138 0x00007ffff373b953 in zend_do_fcall_common_helper_SPEC 
(execute_data=0x7ffff7eac210)
     at /build/php5-5.6.17+dfsg/Zend/zend_vm_execute.h:592
#15139 0x00007ffff36c9dc0 in execute_ex (execute_data=0x7ffff7eac210)
     at /build/php5-5.6.17+dfsg/Zend/zend_vm_execute.h:363
#15140 0x00007ffff367b5b8 in dtrace_execute_ex (execute_data=0x7ffff7eac210)
     at /build/php5-5.6.17+dfsg/Zend/zend_dtrace.c:73
#15141 0x00007ffff368e0b0 in zend_execute_scripts (type=1441122480, 
type at entry=8, retval=0x7fffffe36660,
     retval at entry=0x0, file_count=0, file_count at entry=3) at 
/build/php5-5.6.17+dfsg/Zend/zend.c:1341
#15142 0x00007ffff3629c60 in php_execute_script 
(primary_file=primary_file at entry=0x7fffffffde20)
     at /build/php5-5.6.17+dfsg/main/main.c:2597
#15143 0x00007ffff373cffa in php_handler (r=<optimized out>)
     at /build/php5-5.6.17+dfsg/sapi/apache2handler/sapi_apache2.c:667
#15144 0x00005555555ac2a0 in ap_run_handler (r=r at entry=0x7ffff7e2c0a0) 
at config.c:169
#15145 0x00005555555ac7e9 in ap_invoke_handler (r=0x7ffff7e2c0a0) at 
config.c:433
#15146 0x00005555555c2682 in ap_process_async_request (r=0x7ffff7e2c0a0) 
at http_request.c:317
#15147 0x00005555555c2820 in ap_process_request (r=0x7ffff7e2c0a0) at 
http_request.c:363
#15148 0x00005555555bf122 in ap_process_http_sync_connection 
(c=0x7ffff7e32290) at http_core.c:190
#15149 ap_process_http_connection (c=0x7ffff7e32290) at http_core.c:231
#15150 0x00005555555b5b10 in ap_run_process_connection 
(c=0x7ffff7e32290) at connection.c:41
#15151 0x00007ffff405f7ba in child_main (child_num_arg=1441122480) at 
prefork.c:704
#15152 0x00007ffff405f9c7 in make_child (s=0x7ffff7fc0de0, slot=0) at 
prefork.c:746
#15153 0x00007ffff406070d in prefork_run (_pconf=0x5555557f2f38 
<ap_server_conf>, plog=0x7ffff7fbc028,
     s=0x7ffff7fc0de0) at prefork.c:956
#15154 0x0000555555591e7e in ap_run_mpm (pconf=0x7ffff7fee028, 
plog=0x7ffff7fbc028, s=0x7ffff7fc0de0)
     at mpm_common.c:94
#15155 0x000055555558b3c3 in main (argc=2, argv=0x7fffffffe578) at 
main.c:777