Description of problem:
PHP's passthru function in Red Hat 8 stock PHP/Apache2 is barely functional, if the program it runs returns any significant amount of data, it causes a DoS situation, the server will become very unresponsive, and the query takes much longer than expected.  This could be remotely exploited as a system-wide DoS attack if the user has any script that uses a passthru() function to return data the user requested from an external command.

Version-Release number of selected component (if applicable):
php-4.2.2-8.0.7
httpd-2.0.40-11


How reproducible:
Always

Steps to Reproduce:
1. Create a small php script with one command:

passthru("cat /boot/vmlinuz");
 
2. Request the script through the web server.  The first time it runs it may run quickly and return the proper output, but subsequent times it will randomly take a very long time to return the output, a seeming random amount of time between 10 seconds and 10 minutes.  While the script is running, the server will be very unresponsive.

Note that /boot/vmlinuz is just an example, any command that returns a significant amount of output, (500K+ such as calling ghostscript to generate a PDF/PS file for the user) will cause the condition.  Larger outputs seem to cause the response time to scale up in an exponential growth rate.

Actual results:
Extreme slowdown of server.

Expected results:
Almost instant response with data.

Additional info: