#49098 [Csd]: Using custom session handler causes segfault in session_save_state

From: Date: Thu, 12 Nov 2009 07:16:04 +0000
Subject: #49098 [Csd]: Using custom session handler causes segfault in session_save_state
References: 1  Groups: php.bugs 
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 ID:               49098
 Updated by:       timj@php.net
 Reported By:      bugs at timj dot co dot uk
 Status:           Closed
 Bug Type:         Session related
 Operating System: Linux
 PHP Version:      5.2.10
 New Comment:

Confirmed works for me. Below tested on PHP 5.2 which also seems to
work - could you fix it on that branch too?:

--- ext/mysqli/mysqli.c.orig	2009-07-17 13:17:25.000000000 +0100
+++ ext/mysqli/mysqli.c	2009-11-12 07:10:19.054055576 +0000
@@ -1003,7 +1003,11 @@
 	if (MyG(error_msg)) {
 		efree(MyG(error_msg));
 	}
-	MyG(error_msg) = estrdup(mysql_err);
+	if(mysql_err && *mysql_err) {
+		MyG(error_msg) = estrdup(mysql_err);
+	} else {
+		MyG(error_msg) = NULL;
+	}
 }
 /* }}} */

Many thanks Rasmus (and to Jani/Sriram for your help). 


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

[2009-11-12 01:10:33] rasmus@php.net

Should be fixed now in svn.  Please verify.

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

[2009-11-12 01:09:16] svn@php.net

Automatic comment from SVN on behalf of rasmus
Revision: http://svn.php.net/viewvc/?view=revision&revision=290570
Log: Fix bug #49098

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

[2009-11-11 23:59:51] timj@php.net

I'm not sure if this is useful/correct, but at first pass this stops
the crash:

--- ext/mysqli/mysqli_nonapi.c.orig	2009-10-15 23:34:41.000000000
+0100
+++ ext/mysqli/mysqli_nonapi.c	2009-11-11 23:56:40.271496635 +0000
@@ -46,7 +46,11 @@
 	if (MyG(error_msg)) {
 		efree(MyG(error_msg));
 	}
-	MyG(error_msg) = estrdup(mysql_err);
+	if(mysql_errno!=0) { 
+		MyG(error_msg) = estrdup(mysql_err);
+	} else {
+		MyG(error_msg) = NULL;
+	}
 }
 /* }}} */


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

[2009-11-11 23:55:09] timj@php.net

Stepping through the code though, that patch wouldn't have made any
difference. On the final incantation of php_mysqli_set_error before
crash, estrdup() still gets called:

Breakpoint 1, php_mysqli_set_error (mysql_errno=0, mysql_err=0x10325a7
"") at /path/to/php5.3-200911111930/ext/mysqli/mysqli_nonapi.c:44
44	{
(gdb) step
45		MyG(error_no) = mysql_errno;
(gdb) step
44	{
(gdb) step
45		MyG(error_no) = mysql_errno;
(gdb) step
46		if (MyG(error_msg)) {
(gdb) step
47			efree(MyG(error_msg));
(gdb) next
49		if(mysql_err) { 
(gdb) step
50			MyG(error_msg) = estrdup(mysql_err);


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

[2009-11-11 23:48:50] timj@php.net

Nope, still the same result. (back on the 5.3 snapshot now)

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

The remainder of the comments for this report are too long. To view
the rest of the comments, please view the bug report online at
    http://bugs.php.net/49098

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Edit this bug report at http://bugs.php.net/?id=49098&edit=1

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