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Date: Sat, 26 Dec 2015 14:06:58 +0700
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To: Laruence <laruence@php.net>
Cc: akin.ocal@thomsonreuters.com, PHP internals <internals@lists.php.net>
Content-Type: multipart/alternative; boundary=047d7b2e450ec45da80527c7b7e9
Subject: Re: [PHP-DEV] PHP7 Zend Heap validation
From: pierre.php@gmail.com (Pierre Joye)

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On Dec 26, 2015 12:30 PM, "Xinchen Hui" <laruence@php.net> wrote:
>
> Hey:
>
> On Sat, Dec 26, 2015 at 1:01 PM, <akin.ocal@thomsonreuters.com> wrote:
>
> > Hi everyone,
> >
> > I am working on porting a pre-PHP7 database driver extension to PHP7 for
> > Windows platforms.
> > ( I am using PHP 7.0.1 master branch code and targeting non-ZTS 32 bit
> > PHP7 on Windows Server 2012 R2 )
> > And currently as I did mechanical bits of porting ( compilation issues,
> > getting functionality working
> > mostly followed https://wiki.php.net/phpng-upgrading ) , my extension is
> > only crash-free if I run it with
> > USE_ZEND_ALLOC=0.
> >
> > However with USE_ZEND_ALLOC=1 , I am getting crashes inside
> > zend_mm_alloc_small. As checked with Windbg :
> > ...
> > if (EXPECTED(heap->free_slot[bin_num] != NULL) )
> >                 {
> >                                 zend_mm_free_slot *p =
> > heap->free_slot[bin_num];
> >                                 if ( p->next_free_slot != NULL )
>
>
> > Above , p->next_free_slot is not readable. I believe , currently I am
> > getting the Zend heap corrupt.
> > I am running a test script and  I tried disabling many things ,and
> > enabling one by one to have an idea, from the looks of it , I am getting
> > this issue
> > around a zend_register_resource call but to me that one looks legitimate
> > so I can`t easily pinpoint where the Zend heap gets corrupt.
> >
> > Diffrently from pre-PHP7 where we had full_mem_check , now I can see
> > ZEND_MM_CHECK is placed in memory manager functions.
> >
> > I wanted to ask if there is any chance if we can have a heap integrity
> > checker function , or what would you advise
> > regarding to track down the places in our code corrupting the Zend MM ?
> >
> I am not familar with windows, but if it can be run in linux
>
> you could try with "USE_ZEND_ALLOC=0 valgrind --tool=memcheck "
>
> not sure if there is similar tool on windows
>
>
> thanks
>

On windows you can use a couple of tools to try to find them:
- http://www.softwareverify.com/ (commercial)
- the debugger tools (the standalone tools) contain some limited valgrind
like features
- not directly related but adding --with-static-analyzer=vs is quite useful
too. Latest version is Very effective

Cheers,

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