I have a PHP script for outputting a PNG image. It uses the following functions:
  ImageCreateFromPNG
  ImageColorClosest
  ImageTTFText
  ImageTTFBBox
  ImageLine
  ImagePNG
  ImageDestroy

This worked correctly with PHP 4.0.6 , GD 1.8.4, FreeType 1.3.1. (At the time I first installed PHP4, these were the latest versions of GD and FreeType that behaved properly). 

When I upgraded to PHP 4.3.0RC1, with builtin GD, executing the same script produced memory leak errors in the Apache log:

/usr/local/src/php-4.3.0RC1/ext/gd/libgd/gdhelpers.c(89) :  Freeing 0x082B9CE4 (8 bytes), script=/u/www/paygate/cheque-image.php
Last leak repeated 270 times
/usr/local/src/php-4.3.0RC1/ext/gd/libgd/gdhelpers.c(89) :  Freeing 0x082BDDA4 (8 bytes), script=/u/www/paygate/cheque-image.php
[Mon Nov 18 12:48:04 2002] [notice] child pid 10950 exit signal Segmentation fault (11)
/usr/local/src/php-4.3.0RC1/ext/gd/libgd/gdhelpers.c(89) :  Freeing 0x082B8B84 (8 bytes), script=/u/www/paygate/cheque-image.php
Last leak repeated 264 times

Sometimes the image would still display correctly anyway, and sometimes there would be no output (presumably corresponding to those times that Apache segfaulted, although I did not check this explicitly).

I found that I could correct the problem by not using the builtin GD. This required two steps:
  -- modify my ./configure command to use --with-gd=/path/to/gd instead of --with-gd
  -- modify php_config.h to say HAVE_GD_GD2 0  (in 2 places), ./configure did not pick up automatically that my installed GD was 1.x 

After rebuilding with these GD settings the image was generated correctly with no memory leaks and no segfaults.

I guess therefore that there is something wrong with the builtin GD code.

Here is my ./configure line (that generates the buggy version):

./configure --with-mcrypt --with-mhash --with-mysql=../../mysql --with-gd --enable-versioning --with-ttf --enable-shared --enable-freetype-4bit-antialias-hack --with-informix --with-bz2 --with-gmp --with-zlib --enable-sockets --with-config-dir=/usr/local/etc --enable-debug --with-png-dir=/usr/local --with-jpeg-dir=/usr/local --without-pear --with-apxs

When using "--with-gd", phpinfo() displays "GD Version" as "bundled (2.0 compatible)" and "GIF Support" as "enabled". When using "--with-gd=/path/to/gd", phpinfo() displays "GD Version" as "1.6.2 or higher" and does not display the "GIF Support" line. All other GD fields stay the same (ie. "enabled", except for "FreeType Linkage" which is "with TTF library").

Thanks,
Matt.