[PATCH v3 0/3] MR6004: comctl32: A NULL string fix.

[Aida Jonikienė (＠DodoGTA)]

--
  v3: comctl32/tests: Add tests for NULL strings with edit control WM_GETTEXT message.
      user32: Correctly handle NULL string in WM_GETTEXT AtoW wrapper.

https://gitlab.winehq.org/wine/wine/-/merge_requests/6004

[PATCH v3 1/3] comctl32: Fail on NULL string for edit control WM_GETTEXT message.

[Aida Jonikienė]

From: Aida Jonikienė

Zadig passes a fixed string length to WM_GETTEXT in one place regardless of the string:
https://github.com/pbatard/libwdi/blob/9b23b82a2dd1cbffc16d46c212f92c6bf8c0c...
(which causes a segfault with NULL strings on Wine but not on Windows).

This fixes an unrelated issue in https://bugs.winehq.org/show_bug.cgi?id=54750
(but not the main one).
---
 dlls/comctl32/edit.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/dlls/comctl32/edit.c b/dlls/comctl32/edit.c
index 4b950412617..b7fd50a75e9 100644
--- a/dlls/comctl32/edit.c
+++ b/dlls/comctl32/edit.c
@@ -3183,7 +3183,7 @@ static void EDIT_WM_ContextMenu(EDITSTATE *es, INT x, INT y)
  */
 static INT EDIT_WM_GetText(const EDITSTATE *es, INT count, LPWSTR dst)
 {
-    if (!count)
+    if (!count || !dst)
         return 0;

lstrcpynW(dst, es->text, count);

[PATCH v3 2/3] user32: Correctly handle NULL string in WM_GETTEXT AtoW wrapper.

[Aida Jonikienė]

From: Aida Jonikienė

Spotted in WM_GETTEXT NULL string tests.
---
 dlls/user32/winproc.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/dlls/user32/winproc.c b/dlls/user32/winproc.c
index 5678e75b4e9..eb86572080d 100644
--- a/dlls/user32/winproc.c
+++ b/dlls/user32/winproc.c
@@ -275,6 +275,12 @@ LRESULT WINPROC_CallProcAtoW( winproc_callback_t callback, HWND hwnd, UINT msg,
             DWORD len = wParam * sizeof(WCHAR);

if (!(ptr = get_buffer( buffer, sizeof(buffer), len ))) break;
+            if (!str)
+            {
+                free_buffer( buffer, ptr );
+                ptr = NULL;
+            }
+
             ret = callback( hwnd, msg, wParam, (LPARAM)ptr, result, arg );
             if (wParam)
             {

[PATCH v3 3/3] comctl32/tests: Add tests for NULL strings with edit control WM_GETTEXT message.

[Aida Jonikienė]

From: Aida Jonikienė

---
 dlls/comctl32/tests/edit.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/dlls/comctl32/tests/edit.c b/dlls/comctl32/tests/edit.c
index bce0215ef19..92017c046b2 100644
--- a/dlls/comctl32/tests/edit.c
+++ b/dlls/comctl32/tests/edit.c
@@ -1470,6 +1470,19 @@ static void test_edit_control_6(void)
     ok(ret == strlen(str), "Expected %s, got len %ld\n", str, ret);
     ok(!strcmp(buf, str), "Expected %s, got %s\n", str, buf);

+    ret = SendMessageA(hWnd, WM_GETTEXT, MAXLEN, (LPARAM)NULL);
+    ok(ret == 0, "Expected 0, got len %ld\n", ret);
+    ret = SendMessageA(hWnd, WM_GETTEXT, 0, (LPARAM)NULL);
+    ok(ret == 0, "Expected 0, got len %ld\n", ret);
+
+    if (0) /* Crashes on Windows. */
+    {
+       ret = SendMessageW(hWnd, WM_GETTEXT, MAXLEN, (LPARAM)NULL);
+       ok(ret == 0, "Expected 0, got len %ld\n", ret);
+       ret = SendMessageW(hWnd, WM_GETTEXT, 0, (LPARAM)NULL);
+       ok(ret == 0, "Expected 0, got len %ld\n", ret);
+    }
+
     buf[0] = 0;
     ret = SendMessageA(hWnd, WM_DESTROY, 0, 0);
     todo_wine

[Aida Jonikienė (＠DodoGTA)]

I introduced another Wine failure with that check and a crash on Windows by calling SendMessageW() in the test (I think the first case is fixed and the second case has a `if (0)` over the affected calls)