VM 2.9.9e on PHP 5.4.33 on Linux at http://[somesite.com]/administrator/index.php?option=com_virtuemart&view=product
When adding an image to a product in the backend, my client uploaded a 3.6MB file with a dimension of 5000 by 5000 pixels. Immediately after upload, they got a mainly-white screen. (broken menu on the left, and no top menu etc). I had to log in via ssh and delete the image from the server to regain control.
There were no errors in the error_log, and even with debug mode turned on and display errors set to developer, it still just showed a white screen (in fact a completely white screen).
Resizing the image to 480*480 and uploading again was successful, so I know that the cause of the problem was the size of the image (either the file size, or the dimensions - not sure which).
I'd like to suggest that a check should be made on the file size so that it isn't possible for someone to crash the site by uploading a product image that is too big.
I wonder if the problem was when it tried to generate a thumbnail from the large image. Possibly, but I couldn't see any errors, so I can't be sure. I'm not sure why I could not see any error messages in any of the log files for this specific problem (errors show for other causes).
Hope that helps.
Brian
Does sound like it ran out of memory...
no logging of a GD library problem etc -- in the Apache logs themselves? (normally only accessable by the host if a shared server)