From d227ed5d598340e719eff7156b1aa0a4469e9a6a Mon Sep 17 00:00:00 2001 From: Michael Niedermayer Date: Sun, 10 Mar 2019 01:40:59 +0100 Subject: [PATCH] avcodec/mpeg4videodec: Check idx in mpeg4_decode_studio_block() Fixes: Out of array access Fixes: 13500/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MPEG4_fuzzer-5769760178962432 Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg Reviewed-by: Kieran Kunhya Signed-off-by: Michael Niedermayer --- libavcodec/mpeg4videodec.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/libavcodec/mpeg4videodec.c b/libavcodec/mpeg4videodec.c index 99b1e10620..b6f2ae7b7b 100644 --- a/libavcodec/mpeg4videodec.c +++ b/libavcodec/mpeg4videodec.c @@ -1899,14 +1899,20 @@ static int mpeg4_decode_studio_block(MpegEncContext *s, int32_t block[64], int n code >>= 1; run = (1 << (additional_code_len - 1)) + code; idx += run; + if (idx > 63) + return AVERROR_INVALIDDATA; j = scantable[idx++]; block[j] = sign ? 1 : -1; } else if (group >= 13 && group <= 20) { /* Level value (Table B.49) */ + if (idx > 63) + return AVERROR_INVALIDDATA; j = scantable[idx++]; block[j] = get_xbits(&s->gb, additional_code_len); } else if (group == 21) { /* Escape */ + if (idx > 63) + return AVERROR_INVALIDDATA; j = scantable[idx++]; additional_code_len = s->avctx->bits_per_raw_sample + s->dct_precision + 4; flc = get_bits(&s->gb, additional_code_len);