[FFmpeg-cvslog] avcodec/atrac9dec: Check conditions before apply_band_extension() to avoid out of array read in initialization of unused variables

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Sat Jun 15 21:34:18 2019 +0200| [c5f265bb2468c3e0996329ada11b2792dd9bd1a2] | committer: Michael Niedermayer

avcodec/atrac9dec: Check conditions before apply_band_extension() to avoid out of array read in initialization of unused variables

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>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=c5f265bb2468c3e0996329ada11b2792dd9bd1a2
---

 libavcodec/atrac9dec.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/libavcodec/atrac9dec.c b/libavcodec/atrac9dec.c
index 4d490daeb0..2e23ea44e8 100644
--- a/libavcodec/atrac9dec.c
+++ b/libavcodec/atrac9dec.c
@@ -539,9 +539,6 @@ static inline void apply_band_extension(ATRAC9Context *s, ATRAC9BlockData *b,
         at9_q_unit_to_coeff_idx[g_units[3]],
     };
 
-    if (!b->has_band_ext || !b->has_band_ext_data)
-        return;
-
     for (int ch = 0; ch <= stereo; ch++) {
         ATRAC9ChannelData *c = &b->channel[ch];
 
@@ -751,7 +748,9 @@ static int atrac9_decode_block(ATRAC9Context *s, GetBitContext *gb,
 
     apply_intensity_stereo(s, b, stereo);
     apply_scalefactors    (s, b, stereo);
-    apply_band_extension  (s, b, stereo);
+
+    if (b->has_band_ext && b->has_band_ext_data)
+        apply_band_extension  (s, b, stereo);
 
 imdct:
     for (int i = 0; i <= stereo; i++) {