kernel32: Don't crash accessing an invalid handle in GlobalSize.

dlls/kernel32/heap.c

@@ -807,7 +807,11 @@ SIZE_T WINAPI GlobalSize(HGLOBAL hmem)
    DWORD                retval;
    PGLOBAL32_INTERN     pintern;
 
-   if (!hmem) return 0;
+   if (!((ULONG_PTR)hmem >> 16))
+   {
+       SetLastError(ERROR_INVALID_HANDLE);
+       return 0;
+   }
 
    if(ISPOINTER(hmem))
    {

dlls/kernel32/tests/heap.c

@@ -197,6 +197,13 @@ START_TEST(heap)
     res = GlobalUnlock(gbl);
     ok(res == 1, "Expected 1, got %d\n", res);
 
+    /* GlobalSize on an invalid handle */
+    SetLastError(MAGIC_DEAD);
+    size = GlobalSize((HGLOBAL)0xc042);
+    ok(size == 0, "Expected 0, got %ld\n", size);
+    ok(GetLastError() == ERROR_INVALID_HANDLE,
+       "Expected ERROR_INVALID_HANDLE, got %d\n", GetLastError());
+
     /* ####################################### */
     /* Local*() functions */
     gbl = LocalAlloc(LMEM_MOVEABLE, 0);