Re: Segmentation fault on form posting

Here's the code I mentioned in my last post.  It's included in my distro
NoSQL::PL2SQL

#include "EXTERN.h"
#include "perl.h"
#include "XSUB.h"

#include "ppport.h"

SV* typeis ( SV* what ) ;

SV* typeis ( SV* what )
{
 	if ( SvIOK( what ) )
 		return newSVpvs( "integer" ) ;
 	else if ( SvNOK( what ) )
 		return newSVpvs( "double" ) ;
 	else if ( SvPOK( what ) )
 		return newSVpvs( "string" ) ;

 	return newSVpvs( "unknown" ) ;
}


MODULE = NoSQL::PL2SQL		PACKAGE = NoSQL::PL2SQL::Node

PROTOTYPES: ENABLE

SV* 
typeis( what )
 	SV* what



On Thu, 23 May 2013, Neil Bowers wrote:

> Hi,
> I've got a mod_perl handler which has been working fine for a long time, but
> just recently two people have managed to trigger a seg fault under specific
> circumstances.
>
>  *  They are POSTing form data
>  *  Only happens over https - doesn't happen via http (ie without SSL)
>  *  A certain combination of bytes in the form seems to trigger this.
>     Doesn't appear to be the *number* of bytes, but can't really be sure.
>  *  It only happens if the end-user is on 64-bit Windows (Win 7 only so
>     far), on IE9 or Chrome 26 (27 seems to be ok). Doesn't happen on Firefix
>     on 64bit, or on any browser on 32-bit Windows.
> 
> In my handler, if the first thing I do is print out the POST parameters,
> then the segfault doesn't happen. So it smells like some kind of memory
> overwrite.
> 
> This happens on combinations of:
>
>  *  CentOS 5.5 and 6.3
>  *  openssl 1.0.0d and 1.0.1e
>  *  Apache 2.2.22 and 2.2.24
>  *  Perl 5.12.3 and 5.16.3
>  *  mod_perl 2.0.5, 2.0.7 and 2.0.8
> 
> I'll probably try 5.18, though I don't expect any change with that.
> 
> So now, some questions:
>
>  *  Anyone seen anything like this, and have an idea where to look?
>  *  Any thoughts on where to look / what else to try?
>  *  What's the best approach to tracking this down? Valgrind?
> 
> I'm going to try attaching a debugger to an httpd process to see if I can
> see where it's dying, though I suspect the problem may be happening earlier.
> I'll have a go with valgrind after that.
> 
> Cheers,
> Neil
> 
> 
>