avcodec/alac: Check lpc_quant

lpc_quant of 0 produces undefined behavior, thus disallow this.
If valid samples use this then such a sample would be quite
usefull to confirm the correct&lossles handling of this.

Fixes: libavcodec/alac.c:218:25: runtime error: shift exponent -1 is negative
Fixes: 15273/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_ALAC_fuzzer-5656388535058432
Fixes: 15276/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_ALAC_fuzzer-5761238417539072
Fixes: 15315/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_ALAC_fuzzer-5767260766994432

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This commit is contained in:
Michael Niedermayer 2019-06-19 01:04:07 +02:00
parent e96b7a8ba6
commit a6474b899c
1 changed files with 1 additions and 1 deletions

View File

@ -306,7 +306,7 @@ static int decode_element(AVCodecContext *avctx, AVFrame *frame, int ch_index,
rice_history_mult[ch] = get_bits(&alac->gb, 3);
lpc_order[ch] = get_bits(&alac->gb, 5);
if (lpc_order[ch] >= alac->max_samples_per_frame)
if (lpc_order[ch] >= alac->max_samples_per_frame || !lpc_quant[ch])
return AVERROR_INVALIDDATA;
/* read the predictor table */