From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-px0-f174.google.com ([209.85.212.174]:47238 "EHLO mail-px0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753789Ab0EFOw1 (ORCPT ); Thu, 6 May 2010 10:52:27 -0400 Received: by pxi5 with SMTP id 5so17849pxi.19 for ; Thu, 06 May 2010 07:52:27 -0700 (PDT) Message-ID: <4BE2D7A6.30201@gmail.com> Date: Thu, 06 May 2010 22:52:22 +0800 From: Ang Way Chuang MIME-Version: 1.0 To: linux-media@vger.kernel.org Subject: [PATCH] dvb-core: Fix ULE decapsulation bug when less than 4 bytes of ULE SNDU is packed into the remaining bytes of a MPEG2-TS frame Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-media-owner@vger.kernel.org List-ID: 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. This patch was generated and tested against v2.6.34-rc6. I suspect that this bug was introduced in kernel version 2.6.15, but had not verified it. Care has been taken not to introduce more bug by fixing this bug, but please scrutinize the code because I always produces buggy code. Signed-off-by: Ang Way Chuang --- diff --git a/drivers/media/dvb/dvb-core/dvb_net.c b/drivers/media/dvb/dvb-core/dvb_net.c index 441c064..35a4afb 100644 --- a/drivers/media/dvb/dvb-core/dvb_net.c +++ b/drivers/media/dvb/dvb-core/dvb_net.c @@ -458,8 +458,9 @@ static void dvb_net_ule( struct net_device *dev, const u8 *buf, size_t buf_len ) "field: %u.\n", priv->ts_count, *from_where); /* Drop partly decoded SNDU, reset state, resync on PUSI. */ - if (priv->ule_skb) { - dev_kfree_skb( priv->ule_skb ); + if (priv->ule_skb || priv->ule_sndu_remain) { + if (priv->ule_skb) + dev_kfree_skb( priv->ule_skb ); dev->stats.rx_errors++; dev->stats.rx_frame_errors++; } @@ -534,6 +535,7 @@ 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) @@ -543,6 +545,7 @@ 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; @@ -556,6 +559,7 @@ 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;