[PATCH 0/1] MR8342: user32/tests: Make sure testtext has enough null bytes at the end.

[Yuxuan Shui (＠yshui)]

testtext might be passed to DefWindowProcW in test_aw_conversion_dlgprocA, so
it must have a WCHAR null at the end.

* * *

@nsivov it's also potentially possible for a WCHAR string to go throught W->A conversion then be passed to DefWindowProcW. in that case i am not sure how to guarantee it is wide-null terminated. this doesn't current happen in our test cases though.

[PATCH 1/1] user32/tests: Make sure testtext has enough null bytes at the end.

[Yuxuan Shui]

From: Yuxuan Shui

testtext might be passed to DefWindowProcW in test_aw_conversion_dlgprocA, so
it must have a WCHAR null at the end.
---
 dlls/user32/tests/dialog.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/dlls/user32/tests/dialog.c b/dlls/user32/tests/dialog.c
index 7ea0d13c0f3..d77af346c68 100644
--- a/dlls/user32/tests/dialog.c
+++ b/dlls/user32/tests/dialog.c
@@ -1456,7 +1456,7 @@ static INT_PTR CALLBACK TestControlStyleDlgProc(HWND hdlg, UINT msg,
 }

static const WCHAR testtextW[] = {'W','n','d','T','e','x','t',0};
-static const char *testtext = "WndText";
+static const char *testtext = "WndText\0\0";

enum defdlgproc_text
 {

[Nikolay Sivov (＠nsivov)]

Nikolay Sivov (@nsivov) commented about dlls/user32/tests/dialog.c:
> }
>
> static const WCHAR testtextW[] = {'W','n','d','T','e','x','t',0};
> -static const char *testtext = "WndText";
> +static const char *testtext = "WndText\0\0";

I can only look at this as a way to silence the failure. Could you explain where it fails in code exactly?

[Yuxuan Shui (＠yshui)]

On Tue Jun 17 16:51:10 2025 +0000, Nikolay Sivov wrote:
> I can only look at this as a way to silence the failure. Could you
> explain where it fails in code exactly?

In `test_aw_conversion_dlgproc` we set DLGPROC to `test_aw_conversion_dlgprocA`, then we set "test_mode" to `DLGPROCTEXT_DLGPROCA`, and call `DefDlgProcA(hdlg, WM_SETTEXT, 0, (LPARAM)testtext)`.

So `testtext` gets passed as-is to `test_aw_conversion_dlgprocA`, which then passes it directly to `DefWindowProcW`. Since `DefWindowProcW` wants a wide string, it goes out-of-bound trying to `lstrlenW` it.

[Nikolay Sivov (＠nsivov)]

On Tue Jun 17 17:26:41 2025 +0000, Yuxuan Shui wrote:
> In `test_aw_conversion_dlgproc` we set DLGPROC to
> `test_aw_conversion_dlgprocA`, then we set "test_mode" to
> `DLGPROCTEXT_DLGPROCA`, and call `DefDlgProcA(hdlg, WM_SETTEXT, 0,
> (LPARAM)testtext)`. 
> So `testtext` gets passed as-is to `test_aw_conversion_dlgprocA`, which
> then passes it directly to `DefWindowProcW`. Since `DefWindowProcW`
> wants a wide string, it goes out-of-bound trying to `lstrlenW` it.

I see, in this case it's enough to use "WndText\0". Also please add a code comment why this constant has to be that way, simply stating that it's passed to the ProcW function.