[media] dvb core: only start media entity if not NULL

The logic there tries to start the media entity even if it
doesn't exist, causing this bug:

	[  314.356162] BUG: unable to handle kernel NULL pointer dereference at 0000000000000010
	[  314.356202] IP: [<ffffffffa02ef74c>] media_entity_pipeline_start+0x1c/0x390 [media]

Reported-by: Gert-Jan van der Stroom <gjstroom@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/drivers/media/dvb-core/dvb_frontend.c b/drivers/media/dvb-core/dvb_frontend.c
index aa5306908193..79d2fac5075c 100644
--- a/drivers/media/dvb-core/dvb_frontend.c
+++ b/drivers/media/dvb-core/dvb_frontend.c
@@ -712,7 +712,7 @@ static int dvb_frontend_thread(void *data)
                 /* FIXME: return an error if it fails */
                 dev_info(fe->dvb->device,
                         "proceeding with FE task\n");
-        } else {
+        } else if (fepriv->pipe_start_entity) {
                 ret = media_entity_pipeline_start(fepriv->pipe_start_entity,
                                                   &fepriv->pipe);
                 if (ret)
@@ -830,7 +830,8 @@ restart:
         }
 
 #ifdef CONFIG_MEDIA_CONTROLLER_DVB
-        media_entity_pipeline_stop(fepriv->pipe_start_entity);
+        if (fepriv->pipe_start_entity)
+                media_entity_pipeline_stop(fepriv->pipe_start_entity);
         fepriv->pipe_start_entity = NULL;
 #endif