From 75cec62c0c5a8f79eac39d30c6f748f3cb08f766 Mon Sep 17 00:00:00 2001
From: 82marbag <69267416+82marbag@users.noreply.github.com>
Date: Tue, 6 Jul 2021 16:37:11 -0400
Subject: [PATCH] string: avoid panic strtok on null input

The behavior of strtok when given a NULL input on the first call
is to panic on an unmapped virtual address. This commit changes it
by returning NULL instead of panic.

Signed-off-by: Daniele Ahmed <ahmeddan amazon c;0m >
---
 include/string.h | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/include/string.h b/include/string.h
index 6aaeb5c4..eb36890e 100644
--- a/include/string.h
+++ b/include/string.h
@@ -288,10 +288,13 @@ static inline size_t strcspn(const char *s1, const char *s2) {
 
 static inline char *strtok(char *s, const char *delim) {
 
-    static char *lasts;
+    static char *lasts = NULL;
     int ch;
 
-    if (NULL == s)
+    if (s == NULL && lasts == NULL)
+        return NULL;
+
+    if (s == NULL)
         s = lasts + 1;
 
     do {