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Bug #34515 mysqli_fetch_assoc crashes application
Submitted: 2005-09-15 17:12 UTC Modified: 2009-03-28 14:22 UTC
Votes:12
Avg. Score:4.7 ± 0.6
Reproduced:10 of 10 (100.0%)
Same Version:6 (60.0%)
Same OS:4 (40.0%)
From: jaba at inbox dot lv Assigned:
Status: No Feedback Package: MySQLi related
PHP Version: 5.0.5 OS: Debian GNU/Linux
Private report: No CVE-ID: None
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From: jaba at inbox dot lv
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 [2005-09-15 17:12 UTC] jaba at inbox dot lv
Description:
------------
I am developing on Windows XP but the application production version is supposed to be on Debian. Seems like debian MySQLi is not working properly. I can use mysqli_fetch_row or $result->fetch_row, but whenever I use $result->fetch_assoc() or mysqli_fetch_assoc($result) on the same result, the application crashes and I receive no output at all.

Reproduce code:
---------------
<?php
$mysqli = new mysqli("localhost", "vaipusr", "parolite", "vaipdb");
if (mysqli_connect_errno()) {
   printf("Connect failed: %s\n", mysqli_connect_error());
   exit();
}
$query = "SELECT * FROM acc_users";
if ($result = $mysqli->query($query)) {
	while ($row = $result->fetch_assoc()) {
		echo '<pre>';
		print_r($row);
		echo '</pre>';
	}
   $result->close();
}
$mysqli->close();
?>

Expected result:
----------------
string representation of associated arrays of table rows 


Actual result:
--------------
nothing. application dies whenever you call mysqli_fetch_assoc

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 [2005-09-23 01:00 UTC] php-bugs at lists dot php dot net
No feedback was provided for this bug for over a week, so it is
being suspended automatically. If you are able to provide the
information that was originally requested, please do so and change
the status of the bug back to "Open".
 [2005-10-27 11:15 UTC] mark at tranchant dot plus dot com
I have the same problem. System is self-compiled PHP-5.05 and binary distribution of MySQL-5.0.13, running on self-compiled Apache 2.0.55 on x86 Linux.

mysqli_fetch_row() works as advertised, but mysqli_fetch_assoc() fails silently, both called procedurally or in OO style.
 [2005-10-27 12:05 UTC] mark at tranchant dot plus dot com
In fact, any function that tries to do the assoc thing fails: fetch_object fails, as does fetch_array with a resulttype of MYSQLI_ASSOC or MYSQLI_BOTH. fetch_array works when called with MYSQLI_NUM.

I'm just compiling the latest CVS snapshot, although the diff 'twixt 5.05's ext/mysqli directory and the CVS one doesn't give me much hope...
 [2005-10-27 12:29 UTC] mark at tranchant dot plus dot com
Yeah, I was right. Latest CVS snapshot (php5-STABLE-200510270836) does not fix the issue.
 [2005-10-27 12:34 UTC] tony2001@php.net
Is there any chance to get an account on this server?
 [2005-10-27 13:09 UTC] mark at tranchant dot plus dot com
Not easily, no. I'm not set up for external users. If it would really help, I could try. I've done some more digging:

In ext/mysqli/mysqli.c, there is the following code:

line 653:
 if (fetchtype & MYSQLI_ASSOC) {
    fields = mysql_fetch_fields(result);
 }

line 677:
 if (fetchtype & MYSQLI_ASSOC) {
    if (fetchtype & MYSQLI_NUM) {
       ZVAL_ADDREF(res);
    }
    add_assoc_zval(return_value, fields[i].name, res);
 }

line 687:
 if (fetchtype & MYSQLI_ASSOC) {
    add_assoc_null(return_value, fields[i].name);
 }

If I change the fields[i].name argument to "hello", the offending functions then work. I successfully used fetch_array with MYSQLI_BOTH, and $array['hello'] referred to the last element in the fetched array.

It seems as though the call to mysql_fetch_fields (part of the MySQL API) is failing, which is not being detected by the PHP code. More soon...
 [2005-10-27 14:22 UTC] mark at tranchant dot plus dot com
I've just written a quick C program using the MySQL C API and can confirm that mysql_fetch_fields() works fine. The problem does appear to be with the PHP code. I'll keep looking.
 [2005-10-27 16:10 UTC] mark at tranchant dot plus dot com
Gah. I think I've got as far as my abilities allow.

Basically, if either add_assoc_zval or add_assoc_null are called with anything other than a static string, crash. Even:

char *tmp;
...
sprintf(tmp, "hello");
add_assoc_zval(return_value, tmp, res);

fails, although:

add_assoc_zval(return_value, "hello", res);

does not, and $array['hello'] returns the first value as expected. There is no issue with the mysql_fetch_fields() function: the failure occurs even with that commented out.

I've traced the code path down to _zend_hash_add_or_update(), but I don't know enough to see any problems on the way there.

***********************************

#define add_assoc_zval(__arg, __key, __value) add_assoc_zval_ex(__arg, __key, strlen(__key)+1, __value)

***********************************

ZEND_API int add_assoc_zval_ex(zval *arg, char *key, uint key_len, zval *value)
{
   return zend_symtable_update(Z_ARRVAL_P(arg), key, key_len, (void *) &value, sizeof(zval *), NULL);
}

***********************************

static inline int zend_symtable_update(HashTable *ht, char *arKey, uint nKeyLength, void *pData, uint nDa
taSize, void **pDest)                                   \
{
   HANDLE_NUMERIC(arKey, nKeyLength, zend_hash_index_update(ht, idx, pData, nDataSize, pDest));
   return zend_hash_update(ht, arKey, nKeyLength, pData, nDataSize, pDest);
}

***********************************

#define zend_hash_update(ht, arKey, nKeyLength, pData, nDataSize, pDest) \
   _zend_hash_add_or_update(ht, arKey, nKeyLength, pData, nDataSize, pDest, HASH_UPDATE ZEND_FILE_LINE_CC)

***********************************
 [2005-10-27 20:55 UTC] mark at tranchant dot plus dot com
Upgraded from gcc-3.3.2 to gcc-3.4.4, completely recompiled PHP-5.0.5. No change: bug still there.

Also tried allocating a static buffer (char tmp[64];) and strcpy'ing fields[i].name to it, then using that in the add_assoc calls. No joy there, either.
 [2005-10-28 10:28 UTC] mark at tranchant dot plus dot com
Another data point: mysql_fetch_assoc() (the mysql extension, not the mysqli one) works fine with similar code and calls to add_assoc_zval.

I tried "forward-porting" some of the differences to the mysqli code but just broke it completely.

Is there an easy way to add debug printing to a log file or syslog into the module code? I want to explore the output values from MYSQLI_FETCH_RESOURCE(), which is different from the ZEND_FETCH_RESOURCE used in mysql.
 [2005-11-04 01:00 UTC] php-bugs at lists dot php dot net
No feedback was provided for this bug for over a week, so it is
being suspended automatically. If you are able to provide the
information that was originally requested, please do so and change
the status of the bug back to "Open".
 [2009-03-28 14:06 UTC] Arvids dot Godjuks at gmail dot com
I'm having same issue with my aplication on my Windows home box.

I have Windows XP with SP3.

Apache 2.2.11:
Server version: Apache/2.2.11 (Win32)
Server built:   Dec 10 2008 00:10:06

PHP 5.2.9-1 (built: Mar  5 2009 20:02:28)

And latest MySQL GA -  5.1.33

I have latest PECL pack avaliable for windows.

I'm not really familiar with debugging on windows, so you will have to tell me what to do to get debug info.
 [2009-03-28 14:22 UTC] pajoye@php.net
Do not use mysql 5.1 libmysql DLL with PHP. See the numerous other reports and explainations for more details.
 [2009-03-28 14:24 UTC] Arvids dot Godjuks at gmail dot com
Here is a trace with StraceNT: http://paste.php.lv/685ed5f46f22a328fee5ca8fd917d70a?lang=text
 [2009-03-28 14:42 UTC] Arvids dot Godjuks at gmail dot com
I use one provided by PHP zip package. I just grabed it from php.net, unziped and that's all.
 [2009-04-05 06:11 UTC] tbee at tbee dot org
Yes. I have the same problem. Clean WindowsXP install with only the installer of MySQL, Apache and PHP:

Faulting application httpd.exe, version 2.2.11.0, faulting module php_mysqli.dll, version 5.2.9.9, fault address 0x00002b6b.

All result class methods work fine except the "fetch_*"; I get a result object, the num_rows and field_count return correct values, I can traverse the metadata and display the fieldnames, but whenever I try to access the actual value Apache crashes.

This is the crashing (test) code:

	echo $pResult->field_count;
	for ($i = 0; $i < $pResult->field_count; $i++)
	{
		echo $pResult->fetch_field_direct($i)->name;
	}		
	return $pResult->fetch_assoc();

If the last line is dummified all the fieldname being displayed and there is no crash. Naturally I tried several other method calls to get to the data.
 [2009-07-01 17:07 UTC] roxanne at archinoetics dot com
I found this post, and it worked for me:

http://marc.info/?l=php-internals&m=123825270214607&w=2


Reprinted below:
Put the PHP directory first in your path, doing so will make the mysql extensions use the php's libmysql.
 
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