[PATCH v2 0/1] MR10696: shcore: 0 terminate params->WindowTitle when turning into WCHAR

[Marcus Meissner (＠msmeissn)]

WindowTitle is not necessarily NUL terminated.

Reported-By: Dirk Mueller <[e-mail]>
Found-by: Gemini 3.1 Pro
Signed-off-by: Marcus Meissner <[e-mail]>

--
  v2: shcore: 0 terminate params->WindowTitle when turning into WCHAR
 
https://gitlab.winehq.org/wine/wine/-/merge_requests/10696

[PATCH v2 1/1] shcore: 0 terminate params->WindowTitle when turning into WCHAR

[Marcus Meissner]

From: Marcus Meissner <[e-mail]>

WindowTitle is not necessarily NUL terminated.

Reported-By: Dirk Mueller <[e-mail]>
Found-by: Gemini 3.1 Pro
Signed-off-by: Marcus Meissner <[e-mail]>
---
 dlls/shcore/main.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/dlls/shcore/main.c b/dlls/shcore/main.c
index ea911288c6e..90911ea0a10 100644
--- a/dlls/shcore/main.c
+++ b/dlls/shcore/main.c
@@ -293,8 +293,11 @@ HRESULT WINAPI GetCurrentProcessExplicitAppUserModelID(WCHAR **appid)
     params = RtlGetCurrentPeb()->ProcessParameters;
     if (params->dwFlags & STARTF_TITLEISAPPID)
     {
-        *appid = CoTaskMemAlloc( params->WindowTitle.MaximumLength );
-        if (*appid) wcscpy( *appid, params->WindowTitle.Buffer );
+        *appid = CoTaskMemAlloc( params->WindowTitle.MaximumLength + sizeof(WCHAR));
+        if (*appid) {
+		memcpy( *appid, params->WindowTitle.Buffer, params->WindowTitle.MaximumLength );
+		*appid[params->WindowTitle.MaximumLength/sizeof(WHCAR)] = 0;
+	}
         else ret = E_OUTOFMEMORY;
     }
     else ret = E_FAIL;
-- 
GitLab

https://gitlab.winehq.org/wine/wine/-/merge_requests/10696

[Alexandre Julliard (＠julliard)]

Actually it's guaranteed to be null-terminated, as demonstrated by the fact that GetStartupInfoW directly returns the buffer as string pointer.

-- 
https://gitlab.winehq.org/wine/wine/-/merge_requests/10696#note_137055

[Vishnunithyasoundhar S (＠svishnunithyasoundhar)]

Vishnunithyasoundhar S (@svishnunithyasoundhar) commented about dlls/shcore/main.c:
> params = RtlGetCurrentPeb()->ProcessParameters;
>      if (params->dwFlags & STARTF_TITLEISAPPID)
>      {
> -        *appid = CoTaskMemAlloc( params->WindowTitle.MaximumLength );
> -        if (*appid) wcscpy( *appid, params->WindowTitle.Buffer );
> +        *appid = CoTaskMemAlloc( params->WindowTitle.MaximumLength + sizeof(WCHAR));
> +        if (*appid) {
> +		memcpy( *appid, params->WindowTitle.Buffer, params->WindowTitle.MaximumLength );
> +		*appid[params->WindowTitle.MaximumLength/sizeof(WHCAR)] = 0;

```suggestion:-0+0
		*appid[params->WindowTitle.MaximumLength/sizeof(WCHAR)] = 0;
```

-- 
https://gitlab.winehq.org/wine/wine/-/merge_requests/10696#note_137057

[Vishnunithyasoundhar S (＠svishnunithyasoundhar)]

On Sun Apr 19 11:55:03 2026 +0000, Vishnunithyasoundhar S wrote:
> ```suggestion:-0+0
>       *appid[params->WindowTitle.MaximumLength/sizeof(WCHAR)] = 0;
> ```

Resolving this comment as its unnecessary. I just read the previous comment.

-- 
https://gitlab.winehq.org/wine/wine/-/merge_requests/10696#note_137058