V4L/DVB: dvb-core: Fix ULE decapsulation bug

Fix ULE decapsulation bug when less than 4 bytes of ULE SNDU is packed
into the remaining bytes of a MPEG2-TS frame

ULE (Unidirectional Lightweight Encapsulation RFC 4326) decapsulation
code has a bug that incorrectly treats ULE SNDU packed into the
remaining 2 or 3 bytes of a MPEG2-TS frame as having invalid pointer
field on the subsequent MPEG2-TS frame.

Signed-off-by: Ang Way Chuang <wcang@nav6.org>
Acked-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 11 insertions, 1 deletions

diff --git a/drivers/media/dvb/dvb-core/dvb_net.c b/drivers/media/dvb/dvb-core/dvb_net.c
index f6dac2bb0ac6..6c3a8a06ccab 100644
--- a/drivers/media/dvb/dvb-core/dvb_net.c
+++ b/drivers/media/dvb/dvb-core/dvb_net.c
@@ -351,6 +351,7 @@ static void dvb_net_ule( struct net_device *dev, const u8 *buf, size_t buf_len )
         const u8 *ts, *ts_end, *from_where = NULL;
         u8 ts_remain = 0, how_much = 0, new_ts = 1;
         struct ethhdr *ethh = NULL;
+        bool error = false;
 
 #ifdef ULE_DEBUG
         /* The code inside ULE_DEBUG keeps a history of the last 100 TS cells processed. */
@@ -460,10 +461,16 @@ static void dvb_net_ule( struct net_device *dev, const u8 *buf, size_t buf_len )
 
                                                 /* Drop partly decoded SNDU, reset state, resync on PUSI. */
                                                 if (priv->ule_skb) {
-                                                        dev_kfree_skb( priv->ule_skb );
+                                                        error = true;
+                                                        dev_kfree_skb(priv->ule_skb);
+                                                }
+
+                                                if (error || priv->ule_sndu_remain) {
                                                         dev->stats.rx_errors++;
                                                         dev->stats.rx_frame_errors++;
+                                                        error = false;
                                                 }
+
                                                 reset_ule(priv);
                                                 priv->need_pusi = 1;
                                                 continue;
@@ -535,6 +542,7 @@ static void dvb_net_ule( struct net_device *dev, const u8 *buf, size_t buf_len )
                                 from_where += 2;
                         }
 
+                        priv->ule_sndu_remain = priv->ule_sndu_len + 2;
                         /*
                          * State of current TS:
                          *   ts_remain (remaining bytes in the current TS cell)
@@ -544,6 +552,7 @@ static void dvb_net_ule( struct net_device *dev, const u8 *buf, size_t buf_len )
                          */
                         switch (ts_remain) {
                                 case 1:
+                                        priv->ule_sndu_remain--;
                                         priv->ule_sndu_type = from_where[0] << 8;
                                         priv->ule_sndu_type_1 = 1; /* first byte of ule_type is set. */
                                         ts_remain -= 1; from_where += 1;
@@ -557,6 +566,7 @@ static void dvb_net_ule( struct net_device *dev, const u8 *buf, size_t buf_len )
                                 default: /* complete ULE header is present in current TS. */
                                         /* Extract ULE type field. */
                                         if (priv->ule_sndu_type_1) {
+                                                priv->ule_sndu_type_1 = 0;
                                                 priv->ule_sndu_type |= from_where[0];
                                                 from_where += 1; /* points to payload start. */
                                                 ts_remain -= 1;