V4L/DVB (13968): cx18, fix potential null dereference

Stanse found a potential null dereference in cx18_dvb_start_feed
and cx18_dvb_stop_feed. There is a check for stream being NULL,
but it is dereferenced earlier. Move the dereference after the
check.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Reviewed-by: Andy Walls <awalls@radix.net>
Acked-by: Andy Walls <awalls@radix.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 10 insertions, 8 deletions

diff --git a/drivers/media/video/cx18/cx18-dvb.c b/drivers/media/video/cx18/cx18-dvb.c
index 71ad2d1b4c2..0ad5b63d27f 100644
--- a/drivers/media/video/cx18/cx18-dvb.c
+++ b/drivers/media/video/cx18/cx18-dvb.c
@@ -213,10 +213,14 @@ static int cx18_dvb_start_feed(struct dvb_demux_feed *feed)
 {
         struct dvb_demux *demux = feed->demux;
         struct cx18_stream *stream = (struct cx18_stream *) demux->priv;
-        struct cx18 *cx = stream->cx;
+        struct cx18 *cx;
         int ret;
         u32 v;
 
+        if (!stream)
+                return -EINVAL;
+
+        cx = stream->cx;
         CX18_DEBUG_INFO("Start feed: pid = 0x%x index = %d\n",
                         feed->pid, feed->index);
 
@@ -253,9 +257,6 @@ static int cx18_dvb_start_feed(struct dvb_demux_feed *feed)
         if (!demux->dmx.frontend)
                 return -EINVAL;
 
-        if (!stream)
-                return -EINVAL;
-
         mutex_lock(&stream->dvb.feedlock);
         if (stream->dvb.feeding++ == 0) {
                 CX18_DEBUG_INFO("Starting Transport DMA\n");
@@ -279,13 +280,14 @@ static int cx18_dvb_stop_feed(struct dvb_demux_feed *feed)
 {
         struct dvb_demux *demux = feed->demux;
         struct cx18_stream *stream = (struct cx18_stream *)demux->priv;
-        struct cx18 *cx = stream->cx;
+        struct cx18 *cx;
         int ret = -EINVAL;
 
-        CX18_DEBUG_INFO("Stop feed: pid = 0x%x index = %d\n",
-                        feed->pid, feed->index);
-
         if (stream) {
+                cx = stream->cx;
+                CX18_DEBUG_INFO("Stop feed: pid = 0x%x index = %d\n",
+                                feed->pid, feed->index);
+
                 mutex_lock(&stream->dvb.feedlock);
                 if (--stream->dvb.feeding == 0) {
                         CX18_DEBUG_INFO("Stopping Transport DMA\n");