From Bugzilla Helper:
User-Agent: Mozilla/4.77 [en] (X11; U; Linux 2.2.19 i686)

Description of problem:
If you execute at with invalid environment array it crashes with SIGSEGV.
The problem occur only if environment array contains string without ,,=''
character (without value to the variable.

How reproducible:
Always

Steps to Reproduce:
1. Compile following program: 
int main() 
{
	char * envp[]={ "blah", NULL };
	execle("/usr/bin/at", "at", "now", NULL, envp); 
}
2. Execute it and look how /usr/bin/at crashes.


Actual Results:  at receives SIGSEGV and crashes because of improper
pointer setting


Expected Results:  It should not crash ;)

Additional info:

Tested on at-3.1.8-12 and at-3.1.8-16 (from rawhide) on RH 7.0.
Patch available at: http://cliph.linux.pl/at-3.1.8-nullenv.patch
It doesn't seem to be exploitable.