[PATCH] xfixes: don't dereference a NULL cursor

[Jeremy Huddleston]

Reviewed-by: Jeremy Huddleston <jeremyhu at apple.com>

On Nov 29, 2011, at 3:11 PM, Peter Hutterer wrote:

> If the new cursor is the NULL cursor, don't dereference it and use zeros
> instead.
> 
> Signed-off-by: Peter Hutterer <peter.hutterer at who-t.net>
> ---
> Not sure when this broke given that most of this code hasn't changed in
> ages. Reproducible segfault with
>    xinput create-master "foo"
>    xinput remove-master "foo pointer"
> When the master pointer is removed, CursorDisplayCursor is called with the
> NullCursor, causing a NULL-pointer dereference.
> 
> xfixes/cursor.c |    4 ++--
> 1 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/xfixes/cursor.c b/xfixes/cursor.c
> index 2950e45..53f9f20 100644
> --- a/xfixes/cursor.c
> +++ b/xfixes/cursor.c
> @@ -179,9 +179,9 @@ CursorDisplayCursor (DeviceIntPtr pDev,
> 		ev.type = XFixesEventBase + XFixesCursorNotify;
> 		ev.subtype = XFixesDisplayCursorNotify;
> 		ev.window = e->pWindow->drawable.id;
> -		ev.cursorSerial = pCursor->serialNumber;
> +		ev.cursorSerial = pCursor ? pCursor->serialNumber : 0;
> 		ev.timestamp = currentTime.milliseconds;
> -		ev.name = pCursor->name;
> +		ev.name = pCursor ? pCursor->name : None;
> 		WriteEventsToClient (e->pClient, 1, (xEvent *) &ev);
> 	    }
> 	}
> -- 
> 1.7.7.1
> 
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