[gadamopoulos] 55724: [ntoskrnl] - Fix a crash in KiSystemCall that was caused because PsConvertToGuiThread may have switched to a large kernel stack, but still returned with failure because win32k...

Author: gadamopoulos
Date: Sun Feb 19 22:05:25 2012
New Revision: 55724

URL: http://svn.reactos.org/svn/reactos?rev=55724&view=rev
Log:
[ntoskrnl]
- Fix a crash in KiSystemCall that was caused because PsConvertToGuiThread may have switched to a large kernel stack, but still returned with failure because win32k did not succeed. To fix it reload the trap frame after the call before checking for success.

Modified:
    trunk/reactos/ntoskrnl/ke/i386/traphdlr.c

Modified: trunk/reactos/ntoskrnl/ke/i386/traphdlr.c
URL: http://svn.reactos.org/svn/reactos/trunk/reactos/ntoskrnl/ke/i386/traphdlr.c...
==============================================================================
--- trunk/reactos/ntoskrnl/ke/i386/traphdlr.c [iso-8859-1] (original)
+++ trunk/reactos/ntoskrnl/ke/i386/traphdlr.c [iso-8859-1] Sun Feb 19 22:05:25 2012
@@ -1556,17 +1556,18 @@

/* Convert us to a GUI thread -- must wrap in ASM to get new EBP */
         Result = KiConvertToGuiThread();
+
+        /* Reload trap frame and descriptor table pointer from new stack */
+        TrapFrame = *(volatile PVOID*)&Thread->TrapFrame;
+        DescriptorTable = (PVOID)(*(volatile ULONG_PTR*)&Thread->ServiceTable + Offset);
+
         if (!NT_SUCCESS(Result))
         {
             /* Set the last error and fail */
             //SetLastWin32Error(RtlNtStatusToDosError(Result));
             goto ExitCall;
         }
-        
-        /* Reload trap frame and descriptor table pointer from new stack */
-        TrapFrame = *(volatile PVOID*)&Thread->TrapFrame;
-        DescriptorTable = (PVOID)(*(volatile ULONG_PTR*)&Thread->ServiceTable + Offset);
-        
+
         /* Validate the system call number again */
         if (Id >= DescriptorTable->Limit)
         {