From 1dbb67d39b21ed320edd2b1599b502518250cfd3 Mon Sep 17 00:00:00 2001 From: Michael Niedermayer Date: Thu, 11 Jul 2019 20:02:24 +0200 Subject: [PATCH] avcodec/mpc8: Fixes invalid shift in mpc8_decode_frame() Fixes: left shift of negative value -456 Fixes: 15561/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MPC8_fuzzer-5758130404720640 Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg Suggested-by: James Almer Signed-off-by: Michael Niedermayer --- libavcodec/mpc8.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/libavcodec/mpc8.c b/libavcodec/mpc8.c index 3be2f79a5a..d7baac2f04 100644 --- a/libavcodec/mpc8.c +++ b/libavcodec/mpc8.c @@ -364,8 +364,9 @@ static int mpc8_decode_frame(AVCodecContext * avctx, void *data, for(j = 0; j < SAMPLES_PER_BAND; j += SAMPLES_PER_BAND / 2){ cnt = get_vlc2(gb, q1_vlc.table, MPC8_Q1_BITS, 2); t = mpc8_get_mask(gb, 18, cnt); - for(k = 0; k < SAMPLES_PER_BAND / 2; k++, t <<= 1) - c->Q[ch][off + j + k] = (t & 0x20000) ? (get_bits1(gb) << 1) - 1 : 0; + for(k = 0; k < SAMPLES_PER_BAND / 2; k++) + c->Q[ch][off + j + k] = t & (1 << (SAMPLES_PER_BAND / 2 - k - 1)) + ? (get_bits1(gb) << 1) - 1 : 0; } break; case 2: