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Bug #24556 strip_tags() leaks and crashes
Submitted: 2003-07-09 02:24 UTC Modified: 2007-05-18 14:04 UTC
From: asykakimo at yahoo dot com dot tw Assigned: moriyoshi (profile)
Status: Closed Package: Strings related
PHP Version: 4.3.3RC2-dev OS: Win2000
Private report: No CVE-ID: None
View Developer Edit
 [2003-07-09 02:24 UTC] asykakimo at yahoo dot com dot tw 
Description:
------------
The file_get_contents will cause PHP crash in the following code:
$contents=str_replace("\n","  ",file_get_contents($file));
$contents=strip_tags($contents,'<a><frame><area><meta>');
$tags=(preg_match("|</frameset>|i",$contents))?"src":"href";
$tags=(preg_match("|<meta http-equiv=\"?refresh\"?.*url|i",$contents))?"url":$tags;
echo $tags;

------------------------------------------------------------
The $file variable is come from http://www.starwars.com/index.html

If I replace the file_get_contents with fread function, the php remain this bug too.

Thank

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 [2003-07-09 08:13 UTC] sniper@php.net 
This is not file_get_contents() or any other filesystem function related:

---------------------------------------
/usr/src/web/php/php4_3/ext/standard/string.c(3530) : Block 0x0874B580 status:
Beginning:      OK (allocated on /usr/src/web/php/php4_3/ext/standard/string.c:3339, 1024 bytes)
      End:      Overflown (magic=0x2A8FCC63 instead of 0x2A8FCC84)
                1 byte(s) overflown
---------------------------------------
href/usr/src/web/php/php4_3/ext/standard/string.c(3339) :  Freeing 0x0874B5A4 (1024 bytes), script=t.php


strip_tags() causes the crash. (leaks seem to crash winblows, not linux :)
 [2003-07-09 08:20 UTC] sniper@php.net 
This patch seems to plug the overflow:

Index: string.c
===================================================================
RCS file: /repository/php-src/ext/standard/string.c,v
retrieving revision 1.333.2.32
diff -u -r1.333.2.32 string.c
--- string.c    29 Jun 2003 15:36:10 -0000      1.333.2.32
+++ string.c    9 Jul 2003 13:17:51 -0000
@@ -3336,7 +3336,7 @@
        br = 0;
        if (allow) {
                php_strtolower(allow, allow_len);
-               tbuf = emalloc(PHP_TAG_BUF_SIZE+1);
+               tbuf = emalloc(PHP_TAG_BUF_SIZE+2);
                tp = tbuf;
        } else {
                tbuf = tp = NULL;
 [2003-07-12 04:35 UTC] moriyoshi@php.net 
This bug has been fixed in CVS.

In case this was a PHP problem, snapshots of the sources are packaged
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