V4L/DVB: dvb-core: Fix ULE decapsulation bug
Ang Way Chuang [Thu, 27 May 2010 05:02:09 +0000 (02:02 -0300)]
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>

drivers/media/dvb/dvb-core/dvb_net.c

index f6dac2b..6c3a8a0 100644 (file)
@@ -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;