#45751 [Com]: Php crashes when using auto_prepend_file (out of scope stack address use).

 ID:               45751
 Comment by:       basant dot kukreja at sun dot com
 Reported By:      basant dot kukreja at sun dot com
 Status:           Open
 Bug Type:         Reproducible crash
 Operating System: Solaris 10
 PHP Version:      5.2.6
 New Comment:

The issue was that we are saving stack address execute_data.opline
into
EG(opline_ptr) in execute function in zend_vm_execute.h (line 74). 
	EG(opline_ptr) = &EX(opline);

After function execute is finished, EG(opline_ptr) is not reset to
NULL. This
point to previously used stack. Fix is that before we return we should
set
EG(opline_ptr) to NULL.

Suggested Patch  :
--- Zend/zend_vm_execute_ORIG.h	2008-08-07 18:42:47.876727000 -0700
+++ Zend/zend_vm_execute.h	2008-08-07 18:44:40.481725000 -0700
@@ -90,6 +90,7 @@
 #endif
 
 		if (EX(opline)->handler(&execute_data TSRMLS_CC) > 0) {
+			EG(opline_ptr) = NULL;
       return;
 		}


Previous Comments:
------------------------------------------------------------------------

[2008-08-08 04:35:06] basant dot kukreja at sun dot com

Description:
------------
Stack pointer &execute_data.opline (&EG(opline)) is used beyond the
scope and hence crashes php with auto_preprend_file.

I wrote a small test plugin : test.c and then loaded the plugin into
php using php.ini
extension=test.so

$ ./sapi/cli/php -d "auto_prepend_file=inc.inc" -d
"include_path=/opt2/coolstackbld/svn/CoolStackDev/src/php5/php-5.2.6/tests/lang"
-f /tmp/test.php
Included!
Segmentation Fault (core dumped)


Reproduce code:
---------------
Test plugin location : (skydrive) :
http://yqaghq.blu.livefilestore.com/y1phzvjT69U9PiUNjW9NjakZZ5It3VOAEhADJusnkoorLiwGfeVlK6zTz-8AprvloPplXlNkaHUYD9sS9idFWZhcg/test.c?download

Expected result:
----------------
Normal behaviour

Actual result:
--------------
php crashes

$ pstack core
core 'core' of 23827:   ./sapi/cli/php -d auto_prepend_file=inc.inc -d
include_path=/opt2/cool
 003b8e4c zend_get_executed_lineno (5be8a0, 5897c, ffe39448, 55570c,
ff1531c0, 57400) + 3c
 003d9f78 zend_execute_scripts (8, 0, 3, 1, 2, 5763c) + 11c
 0032d9bc php_execute_script (ffffffff, ffbff2cd, 5be3e0, ffbfefe0, 0,
5ae3a0) + 2b0
 0048e5e4 main     (10000, 5addc8, 2d, 2f, 48cac0, 1ac0) + 1ae4
 000a8f28 _start   (0, 0, 0, 0, 0, 0) + 108

 Debugger showed that it was crashing in line 394 of zend_execute_API.c
:
391  ZEND_API uint zend_get_executed_lineno(TSRMLS_D)
392  {
393  	if (EG(opline_ptr)) {
394  		return active_opline->lineno;

EG(online_ptr) points to arbitrary value ( a pointer value in stack)
and it
crashes in active_opline->lineno.
active_opline->lineno is *EG(opline_ptr)


We found this issue when php was crashing while dtrace plugin was
loaded :
$ ./sapi/cli/php -d "auto_prepend_file=inc.inc" -d
"include_path=/opt2/coolstackbld/svn/CoolStackDev/src/php5/php-5.2.6/tests/lang"
-f /tmp/test.php

To simpilfy thing, I wrote my test plugin and reproduced the crash.




------------------------------------------------------------------------


-- 
Edit this bug report at http://bugs.php.net/?id=45751&edit=1