From 3653108a5c1abe8a0dc8a0e4b7124475c1a5728e Mon Sep 17 00:00:00 2001 From: Michael Niedermayer Date: Sat, 18 Jan 2020 19:28:36 +0100 Subject: [PATCH] avcodec/wmalosslessdec: Fix loop in revert_acfilter() Fixes: out of array read Fixes: 20059/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_WMALOSSLESS_fuzzer-5691776237305856 No testcase except the fuzzed one. Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg Signed-off-by: Michael Niedermayer (cherry picked from commit 5584c0bb945d6010a9d8c22ef3270792022e1761) Signed-off-by: Michael Niedermayer --- libavcodec/wmalosslessdec.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/libavcodec/wmalosslessdec.c b/libavcodec/wmalosslessdec.c index c72b9fdc05..b3446cf49a 100644 --- a/libavcodec/wmalosslessdec.c +++ b/libavcodec/wmalosslessdec.c @@ -826,8 +826,11 @@ static void revert_acfilter(WmallDecodeCtx *s, int tile_size) pred >>= scaling; s->channel_residues[ich][i] += (unsigned)pred; } - for (j = 0; j < order; j++) - prevvalues[j] = s->channel_residues[ich][tile_size - j - 1]; + for (j = order - 1; j >= 0; j--) + if (tile_size <= j) { + prevvalues[j] = prevvalues[j - tile_size]; + }else + prevvalues[j] = s->channel_residues[ich][tile_size - j - 1]; } }