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To: "PHP internals list" <internals@lists.php.net>,
	"Lior Kaplan" <lior.k@zend.com>,
	"Dmitry Stogov" <dmitry@zend.com>
Cc: "Andrea Faulds" <ajf@ajf.me>
References: <CAPJnDK0Q9Z3YUKeK28M_cFpngSWEgEb0-hrBhdSv2rkgdT06cg@mail.gmail.com><8E.46.23339.4FA22565@pb1.pair.com> <CAPJnDK1kPaDWieqBbW4ab4-TatZZ3DtpkRQHrU5Nhdmf-sKvjw@mail.gmail.com>
Date: Tue, 22 Dec 2015 11:36:00 -0600
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Subject: Mysterious crashes (WAS: Re: Pear fetch script problem on PHP 7.0)
From: php_lists@realplain.com ("Matt Wilmas")

Hi all,

Lior, which compiler are you using?  You can still reproduce the problem? 
Can you run it through Valgrind?

I'm getting random crashes I can't figure out on 64-bit Linux after just 
making a very trivial change. :-/  The backtrace is the same up to 
compile_file() (although maybe that doesn't mean much? hmm).

Dmitry, to reproduce, just add another GLOBAL REGISTER variable to 
zend_vm_execute, and then set it in execute_ex().  An empty file will crash 
it.  It does NOT crash with --enable-debug, nor with certain combinations of 
optimization level and global register.

%r12 with -O2 seems to consistently fail, but with -O3 it might be %r13, 
etc.

Now, the question: Is that little change triggering a bug in GCC 4.8?  Or is 
it somehow revealing a PHP problem?!


Thanks,
Matt


----- Original Message -----
From: "Lior Kaplan"
Sent: Monday, November 23, 2015

> Hi,
>
> Thanks Ferenc for checking.
>
> trying to debug this, I've added "echo var_dump($argv);" in the begining 
> of
> the script, but now it segfault.
>
> before:
> sh-3.2# /php-7.0.0RC7/sapi/cli/php -n /php-7.0.0RC7/pear/fetch.php "
> http://5.77.39.20/install-pear-nozlib.phar" pear/install-pear-nozlib.phar
>
> Fatal error: Redefinition of parameter $argv in
> /php-7.0.0RC7/pear/fetch.php on line 3
> sh-3.2# /php-7.0.0RC7/sapi/cli/php -n -m
> [PHP Modules]
> Core
> date
> dom
> filter
> hash
> iconv
> json
> libxml
> mysqlnd
> openssl
> pcre
> PDO
> pdo_mysql
> pdo_pgsql
> pdo_sqlite
> readline
> Reflection
> session
> SimpleXML
> SPL
> sqlite3
> standard
> xml
> xmlreader
> xmlwriter
> zlib
>
> [Zend Modules]
>
> after:
>
> (gdb) r -n /php-7.0.0RC7/pear/fetch.php "
> http://5.77.39.20/install-pear-nozlib.phar" pear/install-pear-nozlib.phar
> Starting program: /php-7.0.0RC7/sapi/cli/php -n
> /php-7.0.0RC7/pear/fetch.php "http://5.77.39.20/install-pear-nozlib.phar"
> pear/install-pear-nozlib.phar
> Reading symbols for shared libraries
> ++++++................................................ done
> Reading symbols for shared libraries ........................ done
>
> Program received signal EXC_BAD_ACCESS, Could not access memory.
> Reason: KERN_INVALID_ADDRESS at address: 0x0000000000000010
> zend_try_compile_cv (result=0x7fff5fbfe440, ast=0x103e6f100) at
> zend_compile.c:2178
> 2178 if (zend_string_equals_literal(name, "this")) {
> (gdb) bt
> #0  zend_try_compile_cv (result=0x7fff5fbfe440, ast=0x103e6f100) at
> zend_compile.c:2178
> #1  0x00000001002b7ff1 in zend_compile_simple_var [inlined] () at
> /php-7.0.0RC7/Zend/zend_compile.c:2226
> #2  0x00000001002b7ff1 in zend_compile_var (result=0x7fff5fbfe440,
> ast=0x103e6f100, type=0) at zend_compile.c:7219
> #3  0x00000001002bb46d in zend_compile_args (ast=0xfffffffffffff2f5,
> fbc=0x103e6f100) at zend_compile.c:2722
> #4  0x00000001002b7e62 in zend_compile_call_common (result=0x7fff5fbfe648,
> args_ast=0xfffffffffffff2f5, fbc=0x10232e050) at zend_compile.c:2810
> #5  0x00000001002ba8e5 in zend_compile_call (result=0x7fff5fbfe648,
> ast=0x103e6f100, type=65523712) at zend_compile.c:3245
> #6  0x00000001002b7366 in zend_compile_expr (result=0x7fff5fbfe648,
> ast=0x103e6f100) at zend_compile.c:7111
> #7  0x00000001002b428f in zend_compile_echo [inlined] () at
> /php-7.0.0RC7/Zend/zend_compile.c:3616
> #8  0x00000001002b428f in zend_compile_stmt (ast=0x103e750d0) at
> zend_compile.c:7007
> #9  0x00000001002b7990 in zend_compile_top_stmt (ast=0x103e750d0) at
> zend_compile.c:6966
> #10 0x00000001002b797d in zend_compile_top_stmt (ast=0x103e750e0) at
> zend_compile.c:6961
> #11 0x00000001002b797d in zend_compile_top_stmt (ast=0x103e770a8) at
> zend_compile.c:6961
> #12 0x000000010029e6f2 in compile_file (file_handle=0x7fff5fbfe728,
> type=65523712) at zend_language_scanner.l:607
> #13 0x00000001002cc4dc in zend_execute_scripts (type=8,
> retval=0x7fff5fbfe990, file_count=1606412688) at zend.c:1422
> #14 0x000000010026a1a9 in php_execute_script (primary_file=0x7fff5fbff6d8)
> at main.c:2471
> #15 0x000000010035dad4 in do_cli [inlined] () at
> /php-7.0.0RC7/sapi/cli/php_cli.c:974
> #16 0x000000010035dad4 in main (argc=1606416352, argv=0x7fff5fbff7e0) at
> php_cli.c:1345
>
> (again, works fine on Linux)
>
>
>
>
> Kaplan
>
>
>
> On Sun, Nov 22, 2015 at 10:51 PM, Andrea Faulds <ajf@ajf.me> wrote:
>
>> Hi Lior,
>>
>> Lior Kaplan wrote:
>>
>>> Fatal error: Redefinition of parameter $argv in
>>> /php-7.0.0RC7/pear/fetch.php on line 3
>>> make: *** [install-pear] Error 255
>>>
>>
>> This is a strange and rather concerning error message. If I look at the
>> source code of /pear/fetch.php in php-src, line three looks like this:
>>
>>     function usage($argv) {
>>
>> $argv here is only specified once in the parameter list, yet it produces
>> an error. Now, presumably this is some sort of conflict with the global
>> variable $argv. But that's a global, not a superglobal, so it really
>> shouldn't cause an error here.
>>
>> This looks like it might be a serious PHP 7 bug.
>>
>> And yet I can't reproduce it by running pear/fetch.php. Is something 
>> weird
>> going on here?
>>
>> Thanks.
>>
>> --
>> Andrea Faulds
>> http://ajf.me/