[tfaber] 65153: [MSGINA] - pszEnvironment is a multi-sz string so make sure to double-null terminate it. Fixes a buffer overrun in winlogon; powered by DPH.

Author: tfaber
Date: Fri Oct 31 17:05:30 2014
New Revision: 65153

URL: http://svn.reactos.org/svn/reactos?rev=65153&view=rev
Log:
[MSGINA]
- pszEnvironment is a multi-sz string so make sure to double-null terminate it. Fixes a
buffer overrun in winlogon; powered by DPH.

Modified:
    trunk/reactos/dll/win32/msgina/msgina.c

Modified: trunk/reactos/dll/win32/msgina/msgina.c
URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/dll/win32/msgina/msgina.c?…
==============================================================================
--- trunk/reactos/dll/win32/msgina/msgina.c	[iso-8859-1] (original)
+++ trunk/reactos/dll/win32/msgina/msgina.c	[iso-8859-1] Fri Oct 31 17:05:30 2014
@@ -30,6 +30,7 @@
 #include <winsvc.h>
 #include <userenv.h>
 #include <ndk/sefuncs.h>
+#include <strsafe.h>
 
 HINSTANCE hDllInstance;
 
@@ -778,15 +779,19 @@
     pProfile->dwType = WLX_PROFILE_TYPE_V2_0;
     pProfile->pszProfile = ProfilePath;
 
-    lpEnvironment = HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY,
-                              (wcslen(pgContext->Domain)+ 14 + 1) * sizeof(WCHAR));
+    cbSize = sizeof(L"LOGONSERVER=\\\\") +
+             wcslen(pgContext->Domain) * sizeof(WCHAR) +
+             sizeof(UNICODE_NULL);
+    lpEnvironment = HeapAlloc(GetProcessHeap(), 0, cbSize);
     if (!lpEnvironment)
     {
         WARN("HeapAlloc() failed\n");
         goto cleanup;
     }
 
-    wsprintfW(lpEnvironment, L"LOGONSERVER=\\\\%s", pgContext->Domain);
+    StringCbPrintfW(lpEnvironment, cbSize, L"LOGONSERVER=\\\\%ls",
pgContext->Domain);
+    ASSERT(wcslen(lpEnvironment) == cbSize / sizeof(WCHAR) - 2);
+    lpEnvironment[cbSize / sizeof(WCHAR) - 1] = UNICODE_NULL;
 
     pProfile->pszEnvironment = lpEnvironment;