avcodec/vorbisdec: fix FASTDIV usage for vr_type == 2

This reverts a hunk from f1ca40ee00 Fixes: out of array read Fixes: 16924/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_VORBIS_fuzzer-5157893162139648 Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
5 years ago · 722fd46965
parent aef24efb0c
commit 722fd46965
1 changed files with 1 additions and 1 deletions
--- a/libavcodec/vorbisdec.c
+++ b/libavcodec/vorbisdec.c
@ -1513,7 +1513,7 @@ static av_always_inline int vorbis_residue_decode_internal(vorbis_context *vc,
                                }

                            } else if (vr_type == 2) {
-                                unsigned voffs_div = FASTDIV(voffset << 1, ch <<1);
+                                unsigned voffs_div = ch == 1 ? voffset : FASTDIV(voffset, ch);
                                unsigned voffs_mod = voffset - voffs_div * ch;

                                for (k = 0; k < step; ++k) {