Re: [Xen-devel] [PATCH for-2.5] vnc: fix segfault

[Anthony PERARD <anthony.perard@xxxxxxxxxx>]

On Wed, Nov 25, 2015 at 08:09:58AM +0100, Gerd Hoffmann wrote:
> Commit "c7628bf vnc: only alloc server surface with clients connected"
> missed one rarely used codepath (cirrus with guest drivers using 2d
> accel) where we have to check for the server surface being present,
> to avoid qemu crashing with a NULL pointer dereference.  Add the check.
> 
> Reported-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>
> Signed-off-by: Gerd Hoffmann <kraxel@xxxxxxxxxx>

This works for me.

Thanks.

> ---
>  ui/vnc.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/ui/vnc.c b/ui/vnc.c
> index c9f2fed..7538405 100644
> --- a/ui/vnc.c
> +++ b/ui/vnc.c
> @@ -931,6 +931,11 @@ static void vnc_dpy_copy(DisplayChangeListener *dcl,
>      int i, x, y, pitch, inc, w_lim, s;
>      int cmp_bytes;
>  
> +    if (!vd->server) {
> +        /* no client connected */
> +        return;
> +    }
> +
>      vnc_refresh_server_surface(vd);
>      QTAILQ_FOREACH_SAFE(vs, &vd->clients, next, vn) {
>          if (vnc_has_feature(vs, VNC_FEATURE_COPYRECT)) {
> -- 
> 1.8.3.1
> 

-- 
Anthony PERARD

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