On Tue, May 13, 2025 at 08:45:00PM -0300, James Almer wrote: > We may write up to 43 bits, so 5 bytes is not enough. > > Fixes: Assertion n>=0 && n<=32 failed at ./libavcodec/get_bits.h:406 > Fixes: > 398527871/clusterfuzz-testcase-minimized-ffmpeg_dem_IAMF_fuzzer-6602025714647040 > > Found-by: continuous fuzzing process > https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg > Signed-off-by: James Almer <jamr...@gmail.com> > --- > libavformat/iamf_parse.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/libavformat/iamf_parse.c b/libavformat/iamf_parse.c > index abedfdb066..11c27ebe98 100644 > --- a/libavformat/iamf_parse.c > +++ b/libavformat/iamf_parse.c > @@ -285,7 +285,7 @@ static int update_extradata(AVCodecParameters *codecpar) > AV_WL16A(codecpar->extradata + 16, AV_RB16A(codecpar->extradata + > 16)); // Byte swap Output Gain > break; > case AV_CODEC_ID_AAC: { > - uint8_t buf[5]; > + uint8_t buf[6]; > > init_put_bits(&pb, buf, sizeof(buf)); > ret = init_get_bits8(&gb, codecpar->extradata, > codecpar->extradata_size); > @@ -304,6 +304,10 @@ static int update_extradata(AVCodecParameters *codecpar) > skip_bits(&gb, 4); > put_bits(&pb, 4, codecpar->ch_layout.nb_channels); // set channel > config > ret = put_bits_left(&pb); > + while (ret >= 32) { > + put_bits32(&pb, get_bits_long(&gb, 32)); > + ret -= 32; > + } > put_bits(&pb, ret, get_bits_long(&gb, ret)); > flush_put_bits(&pb);
bit_copy() from libavcodec/dvdec.c seems doing the same maybe this can be factored somewhere before or after this patch thx [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB Into a blind darkness they enter who follow after the Ignorance, they as if into a greater darkness enter who devote themselves to the Knowledge alone. -- Isha Upanishad
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