===================================================================
RCS file: /cvsrepo/anoncvs/cvs/src/usr.bin/cmp/cmp.c,v
retrieving revision 1.17
retrieving revision 1.18
diff -u -r1.17 -r1.18
--- src/usr.bin/cmp/cmp.c	2018/03/05 16:53:39	1.17
+++ src/usr.bin/cmp/cmp.c	2018/03/05 16:57:37	1.18
@@ -1,4 +1,4 @@
-/*      $OpenBSD: cmp.c,v 1.17 2018/03/05 16:53:39 cheloha Exp $      */
+/*      $OpenBSD: cmp.c,v 1.18 2018/03/05 16:57:37 cheloha Exp $      */
 /*      $NetBSD: cmp.c,v 1.7 1995/09/08 03:22:56 tls Exp $      */
 
 /*
@@ -34,7 +34,9 @@
 #include <sys/stat.h>
 
 #include <err.h>
+#include <errno.h>
 #include <fcntl.h>
+#include <limits.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -44,6 +46,7 @@
 
 int	lflag, sflag;
 
+static off_t get_skip(const char *, const char *);
 static void __dead usage(void);
 
 int
@@ -98,8 +101,8 @@
 	if (pledge("stdio", NULL) == -1)
 		err(ERR_EXIT, "pledge");
 
-	skip1 = argc > 2 ? strtoll(argv[2], NULL, 0) : 0;
-	skip2 = argc == 4 ? strtoll(argv[3], NULL, 0) : 0;
+	skip1 = (argc > 2) ? get_skip(argv[2], "skip1") : 0;
+	skip2 = (argc == 4) ? get_skip(argv[3], "skip2") : 0;
 
 	if (!special) {
 		if (fstat(fd1, &sb1) == -1)
@@ -120,6 +123,23 @@
 		c_regular(fd1, file1, skip1, sb1.st_size,
 		    fd2, file2, skip2, sb2.st_size);
 	return 0;
+}
+
+static off_t
+get_skip(const char *arg, const char *name)
+{
+	off_t skip;
+	char *ep;
+
+	errno = 0;
+	skip = strtoll(arg, &ep, 0);
+	if (arg[0] == '\0' || *ep != '\0')
+		fatalx("%s is invalid: %s", name, arg);
+	if (skip < 0)
+		fatalx("%s is too small: %s", name, arg);
+	if (skip == LLONG_MAX && errno == ERANGE)
+		fatalx("%s is too large: %s", name, arg);
+	return skip;
 }
 
 static void __dead