diff -Nru ppp-2.4.3.orig/pppd/plugins/winbind.c ppp-2.4.3/pppd/plugins/winbind.c
--- ppp-2.4.3.orig/pppd/plugins/winbind.c	2006-05-09 14:39:49.000000000 +0300
+++ ppp-2.4.3/pppd/plugins/winbind.c	2006-07-07 10:09:10.000000000 +0300
@@ -300,8 +300,10 @@
 		close(child_in[1]);
 
 		/* run winbind as the user that invoked pppd */
-		setgid(getgid());
-		setuid(getuid());
+		if (setgid(getgid()) < 0 || setuid(getuid()) < 0) {
+			perror("pppd/winbind: failed to drop privileges");
+			exit(1);
+		}
 		execl("/bin/sh", "sh", "-c", ntlm_auth, NULL);  
 		perror("pppd/winbind: could not exec /bin/sh");
 		exit(1);