[hbelusca] 66223: [WIN32K]: Fix an insecure user buffer reading/writing. Caught by Thomas Faber, thanks! CORE-8322

Author: hbelusca
Date: Wed Feb 11 20:12:30 2015
New Revision: 66223

URL: http://svn.reactos.org/svn/reactos?rev=66223&view=rev
Log:
[WIN32K]: Fix an insecure user buffer reading/writing. Caught by Thomas Faber, thanks!
CORE-8322

Modified:
    trunk/reactos/win32ss/user/ntuser/ntstubs.c

Modified: trunk/reactos/win32ss/user/ntuser/ntstubs.c
URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/win32ss/user/ntuser/ntstub…
==============================================================================
--- trunk/reactos/win32ss/user/ntuser/ntstubs.c	[iso-8859-1] (original)
+++ trunk/reactos/win32ss/user/ntuser/ntstubs.c	[iso-8859-1] Wed Feb 11 20:12:30 2015
@@ -790,6 +790,8 @@
     {
         case UserThreadInitiateShutdown:
         {
+            ULONG CapturedFlags = 0;
+
             ERR("Shutdown initiated\n");
 
             if (ThreadInformationLength != sizeof(ULONG))
@@ -798,7 +800,33 @@
                 break;
             }
 
-            Status = UserInitiateShutdown(Thread, (PULONG)ThreadInformation);
+            /* Capture the caller value */
+            Status = STATUS_SUCCESS;
+            _SEH2_TRY
+            {
+                ProbeForWrite(ThreadInformation, sizeof(CapturedFlags), sizeof(PVOID));
+                CapturedFlags = *(PULONG)ThreadInformation;
+            }
+            _SEH2_EXCEPT(EXCEPTION_EXECUTE_HANDLER)
+            {
+                Status = _SEH2_GetExceptionCode();
+            }
+            _SEH2_END;
+
+            if (NT_SUCCESS(Status))
+                Status = UserInitiateShutdown(Thread, &CapturedFlags);
+
+            /* Return the modified value to the caller */
+            _SEH2_TRY
+            {
+                *(PULONG)ThreadInformation = CapturedFlags;
+            }
+            _SEH2_EXCEPT(EXCEPTION_EXECUTE_HANDLER)
+            {
+                Status = _SEH2_GetExceptionCode();
+            }
+            _SEH2_END;
+
             break;
         }
 
@@ -814,6 +842,7 @@
                 break;
             }
 
+            /* Capture the caller value */
             Status = STATUS_SUCCESS;
             _SEH2_TRY
             {
@@ -844,6 +873,7 @@
                 break;
             }
 
+            /* Capture the caller value */
             Status = STATUS_SUCCESS;
             _SEH2_TRY
             {