[FFmpeg-devel] [PATCH] avcodec/hq_hqa: Check info size

[Michael Niedermayer]

On Sat, May 30, 2020 at 02:09:42AM +0200, Hendrik Leppkes wrote:
> On Sat, May 30, 2020 at 2:01 AM Michael Niedermayer
> <michael at niedermayer.cc> wrote:
> >
> > Fixes: assertion failure
> > Fixes: 21079/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_HQ_HQA_fuzzer-5737046523248640
> >
> > Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> > Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> > ---
> >  libavcodec/hq_hqa.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/libavcodec/hq_hqa.c b/libavcodec/hq_hqa.c
> > index eec2e980b3..8404e80ec8 100644
> > --- a/libavcodec/hq_hqa.c
> > +++ b/libavcodec/hq_hqa.c
> > @@ -321,7 +321,7 @@ static int hq_hqa_decode_frame(AVCodecContext *avctx, void *data,
> >          int info_size;
> >          bytestream2_skip(&ctx->gbc, 4);
> >          info_size = bytestream2_get_le32(&ctx->gbc);
> > -        if (bytestream2_get_bytes_left(&ctx->gbc) < info_size) {
> > +        if (info_size < 0 || bytestream2_get_bytes_left(&ctx->gbc) < info_size) {
> >              av_log(avctx, AV_LOG_ERROR, "Invalid INFO size (%d).\n", info_size);
> >              return AVERROR_INVALIDDATA;
> >          }
> > --
> 
> bytestream2_get_le32 returns an unsigned type, wouldn't it be better
> to make info_size unsigned and avoid the type cast and signed overflow
> that results in this check failing?

The value is ultimatly passed into bytestream2_init()
where its in int so it cannot be beyond the positive signed int range

thx

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

No great genius has ever existed without some touch of madness. -- Aristotle
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