#44703 [Opn->Csd]: htmlspecialchars() does not detect bad character set argument

[felipe]

 ID:               44703
 Updated by:       [EMAIL PROTECTED]
 Reported By:      wharmby at uk dot ibm dot com
-Status:           Open
+Status:           Closed
 Bug Type:         Scripting Engine problem
 Operating System: Windows XP
 PHP Version:      5.2.6RC5
 New Comment:

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/.
 
Thank you for the report, and for helping us make PHP better.




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

[2008-04-11 18:30:20] wharmby at uk dot ibm dot com

Description:
------------
htmlspecialchars() does not always detect bad character set argument.

Problem in the following code around line 850 of ext/standard/html.c:

det_charset:

        if (charset_hint) {
           int found = 0;
                
            /* now walk the charset map and look for the codeset */
                for (i = 0; charset_map[i].codeset; i++) {
                        if (strncasecmp(charset_hint, charset_map[i].codeset, 
len) == 0) {
                           charset = charset_map[i].charset;
                           found = 1;
                           break;
                        }
                }

This uses "len" as the maximum comparison length which is the length 
of the input charset hint. If this happens to match the first few 
characters of a VALID charset then the code fails to detect a bad 
charset. For example  a charset_hint of "125" is allowed as it matches
the first 3 characters of a valid charset; namely "1252".

If code is changed as follows to check the length as are equal first 
then the problem is resolved. 

                for (i = 0; charset_map[i].codeset; i++) {
                        if (len == strlen(charset_map[i].codeset) &&
strncasecmp(charset_hint, charset_map[i].codeset, len) == 0) {
                                charset = charset_map[i].charset;
                                found = 1;
                                break;
                        }
                }

Reproduce code:
---------------
<?php
var_dump( htmlspecialchars("<a href='test'>Test</a>", ENT_COMPAT, 1)
);
var_dump( htmlspecialchars("<a href='test'>Test</a>", ENT_COMPAT, 12)
);
var_dump( htmlspecialchars("<a href='test'>Test</a>", ENT_COMPAT, 125)
);
var_dump( htmlspecialchars("<a href='test'>Test</a>", ENT_COMPAT, 1252)
);
var_dump( htmlspecialchars("<a href='test'>Test</a>", ENT_COMPAT,
12526) );

?>
===Done===

Expected result:
----------------
PHP Warning:  htmlspecialchars(): charset `1' not supported, assuming
iso-8859-1 in  <path to t/c> 
string(35) "&lt;a href='test'&gt;Test&lt;/a&gt;"
PHP Warning:  htmlspecialchars(): charset `12' not supported, assuming
iso-8859-1 in <path to t/c> 
string(35) "&lt;a href='test'&gt;Test&lt;/a&gt;"
PHP Warning:  htmlspecialchars(): charset `125' not supported, assuming
iso-8859-1 in <path to t/c> 
string(35) "&lt;a href='test'&gt;Test&lt;/a&gt;"
string(35) "&lt;a href='test'&gt;Test&lt;/a&gt;"
PHP Warning:  htmlspecialchars(): charset `12526' not supported,
assuming iso-8859-1 in <path to t/c> 
string(35) "&lt;a href='test'&gt;Test&lt;/a&gt;"
===Done===

Actual result:
--------------
string(35) "&lt;a href='test'&gt;Test&lt;/a&gt;"
string(35) "&lt;a href='test'&gt;Test&lt;/a&gt;"
string(35) "&lt;a href='test'&gt;Test&lt;/a&gt;"
string(35) "&lt;a href='test'&gt;Test&lt;/a&gt;"
PHP Warning:  htmlspecialchars(): charset `12526' not supported,
assuming iso-8859-1 in  <path to t/c> 
string(35) "&lt;a href='test'&gt;Test&lt;/a&gt;"
===Done===


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Edit this bug report at http://bugs.php.net/?id=44703&edit=1