[PATCH libX11 v3] XKB: fix XkbGetKeyboardByName with Xming server

[Peter Hutterer]

On Thu, Jan 21, 2016 at 11:54:19AM +0100, Olivier Fourdan wrote:
> XkbGetKeyboardByName relies on flags to read the data from the server.
> 
> If the X server sends us the wrong flags or if a subreply is smaller
> than it should be, XkbGetKeyboardByName will not read all the available
> data and leave data in the buffer, which will cause the next _XReply()
> to fail with:
> 
> [xcb] Extra reply data still left in queue
> [xcb] This is most likely caused by a broken X extension library
> [xcb] Aborting, sorry about that.
> xcb_io.c:576: _XReply: Assertion `!xcb_xlib_extra_reply_data_left' failed.
> Aborted
> 
> Check if there is some extra data left at the end of
> XkbGetKeyboardByName() and discard that data if any is found.
> 
> Many thanks to Peter Hutterer <peter.hutterer at who-t.net> for finding the
> root cause of the issue and Adam Jackson <ajax at redhat.com> for helping
> with the analysis!
> 
> Signed-off-by: Olivier Fourdan <ofourdan at redhat.com>

   43ba0a6..7eb724d  master -> master

thanks!

Cheers,
   Peter


> ---
> v2: bail out if extra data is found, do not return success.
> v3: fix indentation, remove warning message
> 
>  src/xkb/XKBGetByName.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/src/xkb/XKBGetByName.c b/src/xkb/XKBGetByName.c
> index 973052c..efd985b 100644
> --- a/src/xkb/XKBGetByName.c
> +++ b/src/xkb/XKBGetByName.c
> @@ -44,7 +44,7 @@ XkbGetKeyboardByName(Display *dpy,
>  {
>      register xkbGetKbdByNameReq *req;
>      xkbGetKbdByNameReply rep;
> -    int len, extraLen;
> +    int len, extraLen = 0;
>      char *str;
>      XkbDescPtr xkb;
>      int mapLen, codesLen, typesLen, compatLen;
> @@ -204,12 +204,16 @@ XkbGetKeyboardByName(Display *dpy,
>          if (status != Success)
>              goto BAILOUT;
>      }
> +    if (extraLen > 0)
> +	goto BAILOUT;
>      UnlockDisplay(dpy);
>      SyncHandle();
>      return xkb;
>   BAILOUT:
>      if (xkb != NULL)
>          XkbFreeKeyboard(xkb, XkbAllComponentsMask, xTrue);
> +    if (extraLen > 0)
> +        _XEatData(dpy, extraLen);
>      UnlockDisplay(dpy);
>      SyncHandle();
>      return NULL;
> -- 
> 2.5.0
>