[FFmpeg-cvslog] avcodec/atrac9dec: Check that the reused block has succeeded initilization

[Michael Niedermayer]

ffmpeg | branch: release/4.1 | Michael Niedermayer <michael at niedermayer.cc> | Sun Jun 16 20:56:20 2019 +0200| [3d1903acfee865935b73957e1b4df5ae090c93f9] | committer: Michael Niedermayer

avcodec/atrac9dec: Check that the reused block has succeeded initilization

Fixes: global-buffer-overflow
Fixes: 15247/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_ATRAC9_fuzzer-5671602181636096

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg

Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
(cherry picked from commit ac9af7e9a5befa8a554bacbcc59ab2f11203d85e)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=3d1903acfee865935b73957e1b4df5ae090c93f9
---

 libavcodec/atrac9dec.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/libavcodec/atrac9dec.c b/libavcodec/atrac9dec.c
index 805d46f3b8..11b683d136 100644
--- a/libavcodec/atrac9dec.c
+++ b/libavcodec/atrac9dec.c
@@ -71,6 +71,8 @@ typedef struct ATRAC9BlockData {
     int cpe_base_channel;
     int is_signs[30];
 
+    int reuseable;
+
 } ATRAC9BlockData;
 
 typedef struct ATRAC9Context {
@@ -668,6 +670,7 @@ static int atrac9_decode_block(ATRAC9Context *s, GetBitContext *gb,
     if (!reuse_params) {
         int stereo_band, ext_band;
         const int min_band_count = s->samplerate_idx > 7 ? 1 : 3;
+        b->reuseable = 0;
         b->band_count = get_bits(gb, 4) + min_band_count;
         b->q_unit_cnt = at9_tab_band_q_unit_map[b->band_count];
 
@@ -699,6 +702,11 @@ static int atrac9_decode_block(ATRAC9Context *s, GetBitContext *gb,
             }
             b->band_ext_q_unit = at9_tab_band_q_unit_map[ext_band];
         }
+        b->reuseable = 1;
+    }
+    if (!b->reuseable) {
+        av_log(s->avctx, AV_LOG_ERROR, "invalid block reused!\n");
+        return AVERROR_INVALIDDATA;
     }
 
     /* Calculate bit alloc gradient */