[FFmpeg-devel] [PATCH] lavf/tta: Check header and seek table CRC

[James Almer]

Since we don't check for seek table integrity in the decoder anymore,
check it in the demuxer instead (Only tta files are guaranteed to have
one, and it should be valid there).

Check also for header integrity, since the check done in the decoder
is ignored because matroska doesn't store the header at all.

Signed-off-by: James Almer <jamrial at gmail.com>
---
 libavformat/tta.c | 24 +++++++++++++++++++++---
 1 file changed, 21 insertions(+), 3 deletions(-)

diff --git a/libavformat/tta.c b/libavformat/tta.c
index cb04ff4..c9cc65a 100644
--- a/libavformat/tta.c
+++ b/libavformat/tta.c
@@ -21,8 +21,10 @@
 
 #include "libavcodec/get_bits.h"
 #include "avformat.h"
+#include "avio_internal.h"
 #include "internal.h"
 #include "id3v1.h"
+#include "libavutil/crc.h"
 #include "libavutil/dict.h"
 
 typedef struct {
@@ -31,6 +33,12 @@ typedef struct {
     int last_frame_size;
 } TTAContext;
 
+static unsigned long tta_check_crc(unsigned long checksum, const uint8_t *buf,
+                                    unsigned int len)
+{
+    return av_crc(av_crc_get_table(AV_CRC_32_IEEE_LE), checksum, buf, len);
+}
+
 static int tta_probe(AVProbeData *p)
 {
     if (AV_RL32(&p->buf[0]) == MKTAG('T', 'T', 'A', '1') &&
@@ -48,12 +56,13 @@ static int tta_read_header(AVFormatContext *s)
     AVStream *st;
     int i, channels, bps, samplerate;
     uint64_t framepos, start_offset;
-    uint32_t datalen;
+    uint32_t datalen, crc;
 
     if (!av_dict_get(s->metadata, "", NULL, AV_DICT_IGNORE_SUFFIX))
         ff_id3v1_read(s);
 
     start_offset = avio_tell(s->pb);
+    ffio_init_checksum(s->pb, tta_check_crc, UINT32_MAX);
     if (avio_rl32(s->pb) != AV_RL32("TTA1"))
         return -1; // not tta file
 
@@ -72,7 +81,11 @@ static int tta_read_header(AVFormatContext *s)
         return AVERROR_INVALIDDATA;
     }
 
-    avio_skip(s->pb, 4); // header crc
+    crc = ffio_get_checksum(s->pb) ^ UINT32_MAX;
+    if (crc != avio_rl32(s->pb)) {
+        av_log(s, AV_LOG_WARNING, "Header CRC error\n");
+        return AVERROR_INVALIDDATA;
+    }
 
     c->frame_size      = samplerate * 256 / 245;
     c->last_frame_size = datalen % c->frame_size;
@@ -106,13 +119,18 @@ static int tta_read_header(AVFormatContext *s)
     avio_seek(s->pb, start_offset, SEEK_SET);
     avio_read(s->pb, st->codec->extradata, st->codec->extradata_size);
 
+    ffio_init_checksum(s->pb, tta_check_crc, UINT32_MAX);
     for (i = 0; i < c->totalframes; i++) {
         uint32_t size = avio_rl32(s->pb);
         av_add_index_entry(st, framepos, i * c->frame_size, size, 0,
                            AVINDEX_KEYFRAME);
         framepos += size;
     }
-    avio_skip(s->pb, 4); // seektable crc
+    crc = ffio_get_checksum(s->pb) ^ UINT32_MAX;
+    if (crc != avio_rl32(s->pb)) {
+        av_log(s, AV_LOG_WARNING, "Seek table CRC error\n");
+        return AVERROR_INVALIDDATA;
+    }
 
     st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
     st->codec->codec_id = AV_CODEC_ID_TTA;
-- 
1.8.1.5