GetImageSize is not related to GD in anyway. Please provide a sample image, which could be used to duplicate the problem you describe.

This image returns null information on GetImageSize:
http://www.blackpeeps.com/IV/ecnirp/img3d6ea40af403a.jpg

This image does return correct Width and Height info:
http://www.blackpeeps.com/IV/ecnirp/img3e124d90c8123.jpg";

I have even tried downloading the first and uploading back to server to make sure there is not a Binary file transfer issue. No luck. 

Here is a file that my Thumbnail script is not creating a thumbnail for. Well, actually, it creates a Blacked out thumbnail. The script uses ( GetImgageSize , imagecreatetruecolor, and ImageCreateFromJPEG ) 
http://www.blackpeeps.com/IV/ecnirp/img3cae54c4a3771.jpg

This bug has been fixed in CVS.

In case this was a PHP problem, snapshots of the sources are packaged
every three hours; this change will be in the next snapshot. You can
grab the snapshot at http://snaps.php.net/.
 
In case this was a documentation problem, the fix will show up soon at
http://www.php.net/manual/.

In case this was a PHP.net website problem, the change will show
up on the PHP.net site and on the mirror sites in short time.
 
Thank you for the report, and for helping us make PHP better.

This one has been fixed by fixing a streams issue.

I am having the same problem of Getimagesize returning nothing. 
From what i have read, i need to install the latest CVS. But I am not familiar with CVS, and wondering if there's any backdraws resulting from using CVS? Will i have to change my PHP or Apache configuration?
Does it worh it using CVS just to fix the Getimagesize bug?

Thanks in advance
Khaled

Me too!  However, me too over a year later, using php 
4.3.3  (I'm assuming that last years CVS changes are 
into the release version by now)

Certain images, I can't really tell how they differ 
from other images, simply cause getimagesize() to fail.  
If one opens the problem image in an editor like 
Photoshop and resave them as jpegs (as a new file), 
they tend to work OK.  I have tried 'washing' uploaded 
images through Imagemagick, jpegtran and even via:

exec (djpeg <file> | cjpeg -p -r 1 <outputfile>);

I'm effectively resampling the image to a new file 
here, same as opening it in Photoshop and resaving (I 
think/hope)

See samples of working and non-working images here:

http://daisy.studisoup.com/img/ok.jpg (works)
http://daisy.studisoup.com/img/lessok.jpg (doesn't 
work)

I'm seeing this problem on multiple systems (one Red 
Hat ES7, one FreeBSD, one Debian, all on Apache 1.3) 
and with multiple image sources  - although certain 
digital cameras seem to produce the borked images more 
often than others - the LG2100V cameraphone will do it 
every time, as far as I can tell.

I hope this helps, or someone can help me!

Ahem.  Sorry, these urls are the right ones:

http://daisy.studiosoup.com/img/ok.jpg (working)
http://daisy.studiosoup.com/img/lessok.jpg (broken)