From: Michael Niedermayer Date: Wed, 13 May 2020 17:54:42 +0000 (+0200) Subject: avcodec/hcadec: Check or bound indexes X-Git-Url: https://git.sesse.net/?a=commitdiff_plain;h=b7e5c8f67d82550daacce58fae97e1fe3d3fb9aa;p=ffmpeg avcodec/hcadec: Check or bound indexes This causes indexes into scale_conversion_table to wrap around, alternatively they could be clipped, the table be enlarged or we can error out. I have not found a document that specifies what is the correct way to handle this Fixes: out of array access Fixes: 21727/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_HCA_fuzzer-5752477891952640.fuzz Fixes: 22438/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_HCA_fuzzer-5640717790871552 Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg Signed-off-by: Michael Niedermayer --- diff --git a/libavcodec/hcadec.c b/libavcodec/hcadec.c index f25d6c39b66..5fa87319d29 100644 --- a/libavcodec/hcadec.c +++ b/libavcodec/hcadec.c @@ -286,8 +286,8 @@ static void reconstruct_hfr(HCAContext *s, ChannelContext *ch, return; for (int i = 0, k = start_band, l = start_band - 1; i < hfr_group_count; i++){ - for (int j = 0; j < bands_per_hfr_group && k < total_band_count; j++, k++, l--){ - ch->imdct_in[k] = scale_conversion_table[ch->hfr_scale[i] - ch->scale_factors[l]] * ch->imdct_in[l]; + for (int j = 0; j < bands_per_hfr_group && k < total_band_count && l >= 0; j++, k++, l--){ + ch->imdct_in[k] = scale_conversion_table[ (ch->hfr_scale[i] - ch->scale_factors[l]) & 63 ] * ch->imdct_in[l]; } }