[src/trunk]: src/lib/libc/stdlib Avoid NULL pointer arithmetics on environ

[kamil <kamil%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/9fddaf87524e
branches:  trunk
changeset: 745063:9fddaf87524e
user:      kamil <kamil%NetBSD.org@localhost>
date:      Sat Feb 22 10:05:12 2020 +0000

description:
Avoid NULL pointer arithmetics on environ

_env.c:260:9, pointer expression with base 0 overflowed to 0
_env.c:260:9, load of null pointer of type 'char *'

diffstat:

 lib/libc/stdlib/_env.c |  18 ++++++++++--------
 1 files changed, 10 insertions(+), 8 deletions(-)

diffs (40 lines):

diff -r 720273834ddb -r 9fddaf87524e lib/libc/stdlib/_env.c
--- a/lib/libc/stdlib/_env.c    Sat Feb 22 09:59:22 2020 +0000
+++ b/lib/libc/stdlib/_env.c    Sat Feb 22 10:05:12 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: _env.c,v 1.9 2015/01/20 18:31:25 christos Exp $ */
+/*     $NetBSD: _env.c,v 1.10 2020/02/22 10:05:12 kamil Exp $ */
 
 /*-
  * Copyright (c) 2010 The NetBSD Foundation, Inc.
@@ -31,7 +31,7 @@
 
 #include <sys/cdefs.h>
 #if defined(LIBC_SCCS) && !defined(lint)
-__RCSID("$NetBSD: _env.c,v 1.9 2015/01/20 18:31:25 christos Exp $");
+__RCSID("$NetBSD: _env.c,v 1.10 2020/02/22 10:05:12 kamil Exp $");
 #endif /* LIBC_SCCS and not lint */
 
 #include "namespace.h"
@@ -257,13 +257,15 @@
 
        /* Search for an existing environment variable of the given name. */
        num_entries = 0;
-       while (environ[num_entries] != NULL) {
-               if (strncmp(environ[num_entries], name, l_name) == 0 &&
-                   environ[num_entries][l_name] == '=') {
-                       /* We found a match. */
-                       return num_entries;
+       if (environ != NULL) {
+               while (environ[num_entries] != NULL) {
+                       if (strncmp(environ[num_entries], name, l_name) == 0 &&
+                           environ[num_entries][l_name] == '=') {
+                               /* We found a match. */
+                               return num_entries;
+                       }
+                       num_entries ++;
                }
-               num_entries ++;
        }
 
        /* No match found, return if we don't want to allocate a new slot. */