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Bug #29893 Yet another Segmentation fault
Submitted: 2004-08-30 10:47 UTC Modified: 2004-08-30 10:58 UTC
From: n dot favrefelix at free dot fr Assigned: andi (profile)
Status: Closed Package: Scripting Engine problem
PHP Version: 5.0.1 OS: Linux (Mandrake 10)
Private report: No CVE-ID: None
View Developer Edit
 [2004-08-30 10:47 UTC] n dot favrefelix at free dot fr 
Description:
------------
It seems that the following code crashes PHP.
I agree that it's not a good idea to do $table[$table] but I expect something else than a segmentation fault.

Reproduce code:
---------------
<?
$base = 50;
$base[$base] -= 0; // -= crashes PHP, = doesn't

die("Ok");
?>

Expected result:
----------------
A warning or a fatal error, then "OK", but not a segmentation fault...

Actual result:
--------------
Two new lines in my Apache error_log :

[Mon Aug 30 10:42:42 2004] [error] PHP Warning:  Cannot use a scalar value as an array in /www/test.php on line 3
[Mon Aug 30 10:42:42 2004] [notice] child pid 21974 exit signal Segmentation fault (11)

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 [2004-08-30 10:50 UTC] guth at fiifo dot u-psud dot fr 
Additionaly, the crash appears with the followings operators :

-=, += ^=, |=, etc.

<?
$base = 50;
$base[] += 0;

die("ok");
?>

This code doesn't work properly either.
 [2004-08-30 10:51 UTC] tony2001@php.net 
here is the backtrace:
-----
(gdb) r -f /www/index.php
Starting program: /home/dev/php-src_clean/sapi/cli/php -f /www/index.php

Program received signal SIGSEGV, Segmentation fault.
0x00000000 in ?? ()
(gdb) bt
#0  0x00000000 in ?? ()
#1  0x0819e71b in execute (op_array=0x8283d9c) at /home/dev/php-src_clean/Zend/zend_execute.c:1498
#2  0x08179f38 in zend_execute_scripts (type=8, retval=0x0, file_count=3) at /home/dev/php-src_clean/Zend/zend.c:1052
#3  0x08134713 in php_execute_script (primary_file=0xbffff850) at /home/dev/php-src_clean/main/main.c:1633
#4  0x081ac523 in main (argc=3, argv=0xbffff8e4) at /home/dev/php-src_clean/sapi/cli/php_cli.c:943
(gdb) f 1
#1  0x0819e71b in execute (op_array=0x8283d9c) at /home/dev/php-src_clean/Zend/zend_execute.c:1498
1498                    if (EX(opline)->handler(&execute_data TSRMLS_CC)) {
-----
 [2004-08-30 10:56 UTC] derick@php.net 
This works fine in PHP 4, assigning to the zend mastah:

derick@kossu:~$ php-4.3dev
<?
$base = 50;
$base[$base] -= 0; // -= crashes PHP, = doesn't

die("Ok");
?>

Warning: Cannot use a scalar value as an array in - on line 3

Call Stack:
    4.4567      11512   1. {main}() -:0


Variables in local scope:
  $base = 50
 [2004-08-30 10:58 UTC] stas@php.net 
This bug has been fixed in CVS.

Snapshots of the sources are packaged every three hours; this change
will be in the next snapshot. You can grab the snapshot at
http://snaps.php.net/.
 
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