[PATCH 3/3] drm: Avoid dereferencing a NULL mstb in drm_dp_mst_handle_up_req()

[Imre Deak]

On Thu, May 12, 2016 at 04:00:40PM +0300, Imre Deak wrote:
> In case of an unknown broadcast message is sent mstb will remain unset,
> so check for this.
> 
> CC: Dave Airlie <airlied at redhat.com>
> Signed-off-by: Imre Deak <imre.deak at intel.com>

Could someone review 2/3 and 3/3 in this patchset? 1/3 was NAK'd and
otherwise isn't needed anymore.

Thanks,
Imre

> ---
>  drivers/gpu/drm/drm_dp_mst_topology.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
> index 12c0ab3..412b9ca 100644
> --- a/drivers/gpu/drm/drm_dp_mst_topology.c
> +++ b/drivers/gpu/drm/drm_dp_mst_topology.c
> @@ -2334,7 +2334,9 @@ static int drm_dp_mst_handle_up_req(struct drm_dp_mst_topology_mgr *mgr)
>  			DRM_DEBUG_KMS("Got RSN: pn: %d avail_pbn %d\n", msg.u.resource_stat.port_number, msg.u.resource_stat.available_pbn);
>  		}
>  
> -		drm_dp_put_mst_branch_device(mstb);
> +		if (mstb)
> +			drm_dp_put_mst_branch_device(mstb);
> +
>  		memset(&mgr->up_req_recv, 0, sizeof(struct drm_dp_sideband_msg_rx));
>  	}
>  	return ret;
> -- 
> 2.5.0
> 
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