"grep bug"

[Olatunji Oluwabukunmi Ruwase]

Hi,
 I came across what seems to be a bug in grep-2.5.1. The problem is the
result of memchr(which could be NULL) is passed to a pointer variable
"end", "end" is then incremented without checking whether or not it is
NULL. "end"(now 0x01) is finally used in a pointer difference operation.
 This following snippet from src/search.c:582 is the code
********************************************************
  end = memchr (beg + len, eol, (buf + size) - (beg + len));
  end++;
  while (buf < beg && beg[-1] != eol)
    --beg;
  *match_size = end - beg;
*********************************************************
 Running grep with the following command line triggers this situation
 echo " " | grep -F -e ''

This error was flagged by a dynamic bounds checking tool I am working on
while running the regression tests. I would appreciate if you could take a
look at it, to confirm it as a bug or some programming idiom in which case
my tool is generating false alarm
 Thank you

tunji