php71-xdebug @2.6.0_0 trap 6 when executing script which generates a PHP Notice during an eval().

[iakoder]

I thought this might be an xdebug issue so I reported this to ​https://bugs.xdebug.org/view.php?id=1545 Turns out it's more likely a macports/xdebug/php issue.

The following script when executed in PHP 7.0 or 7.1 w/ xdebug 2.6.0 crashes when executed with MacPorts php70 or php71 with xdebug 2.6.0. Without xdebug it works fine. Using PHP 5.6 w/ xdebug 2.5.5 works fine. Using PHP 7.1.16 + xdebug 2.6.0 built from source works fine.

Crashes

$t = "\$arr[0] .= \"abc\";"; echo "$t\n"; eval($t); echo "Done\n";

Doesn't Crash

$t = "\$arr[0] = \"abc\";"; echo "$t\n"; eval($t); echo "Done\n";

Relevant Versions:

macOS High Sierra
10.31.2
XCode 9.3 9E145
MacPorts 2.4.3
php70 @7.0.29_0+libedit
php70-xdebug @2.6.0_0
php71 @7.1.16_0+libedit
php71-xdebug @2.6.0_0

PHP 7.1.16 + xdebug 2.6.0 crashes

$ php71 --version
PHP 7.1.16 (cli) (built: Apr  2 2018 22:57:16) ( NTS )
Copyright (c) 1997-2018 The PHP Group
Zend Engine v3.1.0, Copyright (c) 1998-2018 Zend Technologies
    with Zend OPcache v7.1.16, Copyright (c) 1999-2018, by Zend Technologies
    with Xdebug v2.6.0, Copyright (c) 2002-2018, by Derick Rethans

$ php71  -r '$t = "\$arr[0] .= \"abc\";"; echo "$t\n"; eval($t); echo "Done\n";'
$arr[0] .= "abc";
php71(20604,0x7fffb6ad6340) malloc: *** error for object 0x10cd30dbf: pointer being freed was not allocated
*** set a breakpoint in malloc_error_break to debug
Abort trap: 6

A version that doesn't generate notices doesn't fail

$ php71  -r '$t = "\$arr[0] = \"abc\";"; echo "$t\n"; eval($t); echo "Done\n";'
$arr[0] = "abc";
Done

PHP 7.0.29 w/ xdebug 2.6.0 crashes

$ php70 --version
PHP 7.0.29 (cli) (built: Mar 30 2018 05:11:11) ( NTS )
Copyright (c) 1997-2017 The PHP Group
Zend Engine v3.0.0, Copyright (c) 1998-2017 Zend Technologies
    with Zend OPcache v7.0.29, Copyright (c) 1999-2017, by Zend Technologies
    with Xdebug v2.6.0, Copyright (c) 2002-2018, by Derick Rethans

$ php70  -r '$t = "\$arr[0] .= \"abc\";"; echo "$t\n"; eval($t); echo "Done\n";'
$arr[0] .= "abc";
php70(20607,0x7fffb6ad6340) malloc: *** error for object 0x10ae81dbf: pointer being freed was not allocated
*** set a breakpoint in malloc_error_break to debug
Abort trap: 6

Version that doesn't generate notices during eval works fine

$ php70  -r '$t = "\$arr[0] = \"abc\";"; echo "$t\n"; eval($t); echo "Done\n";'
$arr[0] = "abc";
Done

After disabling xdebug everything works fine

$ php71 --version
PHP 7.1.16 (cli) (built: Apr  2 2018 22:57:16) ( NTS )
Copyright (c) 1997-2018 The PHP Group
Zend Engine v3.1.0, Copyright (c) 1998-2018 Zend Technologies
    with Zend OPcache v7.1.16, Copyright (c) 1999-2018, by Zend Technologies
dwilks-mbp-l:xdebug-2.6.0 dwilks$ 

$ php71  -r '$t = "\$arr[0] .= \"abc\";"; echo "$t\n"; eval($t); echo "Done\n";'
$arr[0] .= "abc";
Done

$ php70 --version
PHP 7.0.29 (cli) (built: Mar 30 2018 05:11:11) ( NTS )
Copyright (c) 1997-2017 The PHP Group
Zend Engine v3.0.0, Copyright (c) 1998-2017 Zend Technologies
    with Zend OPcache v7.0.29, Copyright (c) 1999-2017, by Zend Technologies

$ php70  -r '$t = "\$arr[0] .= \"abc\";"; echo "$t\n"; eval($t); echo "Done\n";'
$arr[0] .= "abc";
Done

PHP 5.6 works fine with xdebug 2.5.5

$ php56 --version
PHP 5.6.35 (cli) (built: Mar 30 2018 07:58:04) 
Copyright (c) 1997-2016 The PHP Group
Zend Engine v2.6.0, Copyright (c) 1998-2016 Zend Technologies
    with Zend OPcache v7.0.6-dev, Copyright (c) 1999-2016, by Zend Technologies
    with Xdebug v2.5.5, Copyright (c) 2002-2017, by Derick Rethans

$ php56  -r '$t = "\$arr[0] .= \"abc\";"; echo "$t\n"; eval($t); echo "Done\n";'
$arr[0] .= "abc";
Done

With PHP 7.1.6 + xdebug 2.6.0 built from source:

$ /usr/local/php71/bin/php --version
PHP 7.1.16 (cli) (built: Apr 17 2018 14:04:52) ( NTS DEBUG )
Copyright (c) 1997-2018 The PHP Group
Zend Engine v3.1.0, Copyright (c) 1998-2018 Zend Technologies
    with Xdebug v2.6.0, Copyright (c) 2002-2018, by Derick Rethans

$ /usr/local/php71/bin/php  -r '$t = "\$arr[0] .= \"abc\";"; echo "$t\n"; eval($t); echo "Done\n";'
$arr[0] .= "abc";
Done

PHP configuration:

./configure --prefix=/usr/local/php71 \
            --enable-debug \
            --with-config-file-path=/usr/local/php71/etc \
            --with-config-file-scan-dir=/usr/local/php71/etc/conf.d \
            --disable-all \
            --enable-bcmath \
            --enable-ctype \
            --enable-dom \
            --enable-filter  \
            --enable-hash  \
            --enable-json  \
            --enable-libxml \
            --enable-pdo  \
            --enable-session \
            --enable-simplexml \
            --enable-tokenizer \
            --enable-xml \
            --enable-xmlreader \
            --enable-xmlwriter \
            --with-bz2=/opt/local \
            --with-mhash=/opt/local \
            --with-pcre-regex=/opt/local \
            --with-libxml-dir=/opt/local \
            --with-zlib=/opt/local \
            --without-pear \
            --disable-cgi \
            --enable-cli \
            --enable-fileinfo \
            --enable-phar \
            --disable-fpm \
            --with-apxs2=/opt/local/bin/apxs
make
make test
sudo make install

xdebug configuration:

/usr/local/php71/bin/phpize
./configure --prefix=/usr/local/php71 --with-php-config=/usr/local/php71/bin/php-config
make
make test
sudo make install
sudo bash -c 'echo zend_extension=xdebug.so > /usr/local/php71/etc/conf.d/xdebug.ini'
/usr/local/php71/bin/php -i | grep xdebug

[ryandesign (Ryan Carsten Schmidt)]

Replying to iakoder:

I thought this might be an xdebug issue so I reported this to ​https://bugs.xdebug.org/view.php?id=1545 Turns out it's more likely a macports/xdebug/php issue.

If you can explain in what way this is our issue and what we need to do to fix it, I'm happy to do so.

[iakoder]

I thought this might be an xdebug issue so I reported this to ​​https://bugs.xdebug.org/view.php?id=1545 Turns out it's more likely a macports/xdebug/php issue.

If you can explain in what way this is our issue and what we need to do to fix it, I'm happy to do so.

I don't know that it is a MacPorts problem. I only know that it only happens when I use MacPorts php70+php70-xdebug or php71+php71-xdebug. It doesn't happen when I use my own compiled-from-source php71+xdebug with matching versions of MacPorts php71. Derick, the xdebug author, couldn't reproduce it on his Linux system.

I'm more than willing to help narrow it down if I can.

[iakoder]

Apologies. My php.ini was slightly different between macports in /opt/local/etc/php71 and built-from-scratch /usr/local/php71/etc. Copied macports into /usr/local and boom. Back to Derick.

Feel free to close, reject, whatever.

$ /usr/local/php71/bin/php  -r '$t = "\$arr[0] .= \"abc\";"; echo "$t\n"; eval($t); echo "Done\n";'
$arr[0] .= "abc";
php(30348,0x7fffb6ad6340) malloc: *** error for object 0x10ecaa1ec: pointer being freed was not allocated
*** set a breakpoint in malloc_error_break to debug
Abort trap: 6