Description of problem:

We have a NIS-bound system with 'passwd: compat' in /etc/nsswitch.conf.  The final line in /etc/passwd on this was system was:

  +:

On this system, "finger" would segfault when passed a username as an
argument.  On line 188 in finger/util.c, finger was calling strncpy()
like this:

  int                         
  match(struct passwd *pw, const char *user)
  {                               
          char *p;                        
          int i, j, ct, rv=0;             
          char *rname;            
                          
          strncpy(tbuf, pw->pw_gecos, TBUFLEN);

With our /etc/passwd file configured as described, pw->pw_gecos would
have a NULL rather than empty value, causing strncpy() to segfault.
An ideal fix would be to have match() return 0 if pw->pw_gecos is
NULL, as in this patch:

diff --git a/finger/util.c b/finger/util.c
index 8e28d63..c82bc86 100644
--- a/finger/util.c
+++ b/finger/util.c
@@ -186,6 +186,9 @@ match(struct passwd *pw, const char *user)
        int i, j, ct, rv=0;
        char *rname;
 
+       if (pw->pw_gecos == NULL)
+               return 0;
+
        strncpy(tbuf, pw->pw_gecos, TBUFLEN);
        tbuf[TBUFLEN-1] = 0;  /* guarantee null termination */
        p = tbuf;