From 4333718b357a9ad195031e5d0ea080d37677b795 Mon Sep 17 00:00:00 2001 From: Michael Niedermayer Date: Thu, 23 Jul 2020 23:41:27 +0200 Subject: [PATCH] avcodec/alac: Check decorr_shift to avoid invalid shift Later the decorrelate_stereo call is guarded by channels == 2 and non-zero decorr_left_weight. Make sure decorr_shift is in the expected shift range for that case. Fixes: shift exponent 128 is too large for 32-bit type 'int' Fixes: 23860/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_ALAC_fuzzer-5751138914402304 Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg Reviewed-by: Alexander Strasser Signed-off-by: Michael Niedermayer --- libavcodec/alac.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/libavcodec/alac.c b/libavcodec/alac.c index bf054062300..9040673528a 100644 --- a/libavcodec/alac.c +++ b/libavcodec/alac.c @@ -302,6 +302,9 @@ static int decode_element(AVCodecContext *avctx, AVFrame *frame, int ch_index, decorr_shift = get_bits(&alac->gb, 8); decorr_left_weight = get_bits(&alac->gb, 8); + if (channels == 2 && decorr_left_weight && decorr_shift > 31) + return AVERROR_INVALIDDATA; + for (ch = 0; ch < channels; ch++) { prediction_type[ch] = get_bits(&alac->gb, 4); lpc_quant[ch] = get_bits(&alac->gb, 4); -- 2.39.5