Piotr Caban : msvcrt: Don't crash on NULL argument in _wgetenv.

[Alexandre Julliard]

Module: wine
Branch: master
Commit: d812af3f12434a4671f1aa98fcc5fb11ffa9826b
URL:    https://gitlab.winehq.org/wine/wine/-/commit/d812af3f12434a4671f1aa98fcc5fb1...

Author: Piotr Caban <piotr(a)codeweavers.com>
Date:   Wed Feb 15 13:38:38 2023 +0100

msvcrt: Don't crash on NULL argument in _wgetenv.

---

 dlls/msvcrt/environ.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/dlls/msvcrt/environ.c b/dlls/msvcrt/environ.c
index 145f7d0640f..a2626a85c30 100644
--- a/dlls/msvcrt/environ.c
+++ b/dlls/msvcrt/environ.c
@@ -50,12 +50,15 @@ char * CDECL getenv(const char *name)
 }
 
 /*********************************************************************
- *		_wgetenv (MSVCRT.@)
+ *              _wgetenv (MSVCRT.@)
  */
 wchar_t * CDECL _wgetenv(const wchar_t *name)
 {
     wchar_t **env;
-    unsigned int length=wcslen(name);
+    size_t len;
+
+    if (!MSVCRT_CHECK_PMT(name != NULL)) return NULL;
+    len = wcslen(name);
 
     /* Initialize the _wenviron array if it's not already created. */
     if (!MSVCRT__wenviron)
@@ -65,7 +68,7 @@ wchar_t * CDECL _wgetenv(const wchar_t *name)
     {
         wchar_t *str = *env;
         wchar_t *pos = wcschr(str,'=');
-        if (pos && ((pos - str) == length) && !_wcsnicmp(str,name,length))
+        if (pos && ((pos - str) == len) && !_wcsnicmp(str, name, len))
         {
             TRACE("(%s): got %s\n", debugstr_w(name), debugstr_w(pos + 1));
             return pos + 1;