ntoskrnl.exe/tests: Fix path buffer allocation size.

dlls/ntoskrnl.exe/tests/ntoskrnl.c

@@ -144,7 +144,7 @@ static void main_test(void)
     WCHAR temppathW[MAX_PATH], pathW[MAX_PATH];
     struct test_input *test_input;
     UNICODE_STRING pathU;
-    DWORD written, read;
+    DWORD len, written, read;
     LONG new_failures;
     char buffer[512];
     HANDLE okfile;
@@ -155,13 +155,14 @@ static void main_test(void)
     GetTempFileNameW(temppathW, dokW, 0, pathW);
     pRtlDosPathNameToNtPathName_U( pathW, &pathU, NULL, NULL );
 
-    test_input = heap_alloc( offsetof( struct test_input, path[pathU.Length / sizeof(WCHAR)]) );
+    len = pathU.Length + sizeof(WCHAR);
+    test_input = heap_alloc( offsetof( struct test_input, path[len / sizeof(WCHAR)]) );
     test_input->running_under_wine = !strcmp(winetest_platform, "wine");
     test_input->winetest_report_success = winetest_report_success;
     test_input->winetest_debug = winetest_debug;
-    memcpy(test_input->path, pathU.Buffer, pathU.Length + sizeof(WCHAR));
+    memcpy(test_input->path, pathU.Buffer, len);
     res = DeviceIoControl(device, IOCTL_WINETEST_MAIN_TEST, test_input,
-                          offsetof( struct test_input, path[pathU.Length / sizeof(WCHAR)]),
+                          offsetof( struct test_input, path[len / sizeof(WCHAR)]),
                           &new_failures, sizeof(new_failures), &written, NULL);
     ok(res, "DeviceIoControl failed: %u\n", GetLastError());
     ok(written == sizeof(new_failures), "got size %x\n", written);