Description of problem:
When using the command 
grep --color=auto --ignore-case --before-context 1 --after-context=4 --max-count
10 SEARCH-ARG FILE
a segfault is produced in for the _last_ match in search.c

Version-Release number of selected component (if applicable):
grep-2.5.1-31.4

How reproducible:
100%

Actual results:
grep segfaults.

Expected results:
colorized context printed up to match times.

Additional info:
The faulting function is src/search.c::EGexecute::memchr().  The starting
address "beg" is passed as 1.  This was caused by the NULL return from the
previous call to memchr() and the loop continues.