The 0x (or 0X) prefix in base 16 is optional so only skip over the

prefix if the character following it is a valid hex char.  The C99
standard is clear that given the string "0xy" zero should be returned
and endptr set to point to the "x".  OK deraadt@ espie@

1 files changed, 3 insertions, 3 deletions

diff --git a/src/lib/libc/stdlib/strtoul.c b/src/lib/libc/stdlib/strtoul.c
index 98e8abcbdb..6667bea8fa 100644
--- a/src/lib/libc/stdlib/strtoul.c
+++ b/src/lib/libc/stdlib/strtoul.c
@@ -1,4 +1,4 @@
-/*      $OpenBSD: strtoul.c,v 1.10 2015/09/13 08:31:48 guenther Exp $ */
+/*      $OpenBSD: strtoul.c,v 1.11 2017/07/06 16:23:11 millert Exp $ */
 /*
  * Copyright (c) 1990 The Regents of the University of California.
  * All rights reserved.
@@ -69,8 +69,8 @@ strtoul(const char *nptr, char **endptr, int base)
                 if (c == '+')
                         c = *s++;
         }
-        if ((base == 0 || base == 16) &&
-            c == '0' && (*s == 'x' || *s == 'X')) {
+        if ((base == 0 || base == 16) && c == '0' &&
+            (*s == 'x' || *s == 'X') && isxdigit((unsigned char)s[1])) {
                 c = s[1];
                 s += 2;
                 base = 16;