[FFmpeg-cvslog] avcodec/alsdec: Check that input space for header exists in read_diff_float_data()

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Fri Oct  4 19:35:15 2019 +0200| [09581f7923ed9af7719762868e8f1ff626ea8374] | committer: Michael Niedermayer

avcodec/alsdec: Check that input space for header exists in read_diff_float_data()

Fixes: Timeout (21sec -> 8sec)
Fixes: 17832/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_ALS_fuzzer-5737092172218368

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=09581f7923ed9af7719762868e8f1ff626ea8374
---

 libavcodec/alsdec.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/libavcodec/alsdec.c b/libavcodec/alsdec.c
index fafc3a757b..4bc0e2bd84 100644
--- a/libavcodec/alsdec.c
+++ b/libavcodec/alsdec.c
@@ -1475,6 +1475,9 @@ static int read_diff_float_data(ALSDecContext *ctx, unsigned int ra_frame) {
         ff_mlz_flush_dict(ctx->mlz);
     }
 
+    if (avctx->channels * 8 > get_bits_left(gb))
+        return AVERROR_INVALIDDATA;
+
     for (c = 0; c < avctx->channels; ++c) {
         if (use_acf) {
             //acf_flag