On Fri, Apr 22, 2016 at 04:04:54PM +0200, wm4 wrote:
> On Fri, 22 Apr 2016 11:59:14 +0200
> Michael Niedermayer <mich...@niedermayer.cc> wrote:
>
> > On Fri, Apr 22, 2016 at 09:11:52AM +0200, wm4 wrote:
> > > On Fri, 22 Apr 2016 05:14:30 +0200
> > > Michael Niedermayer <mich...@niedermayer.cc> wrote:
> > >
> > > > Signed-off-by: Michael Niedermayer <mich...@niedermayer.cc>
> > > > ---
> > > > libavcodec/utils.c | 1 +
> > > > 1 file changed, 1 insertion(+)
> > > >
> > > > diff --git a/libavcodec/utils.c b/libavcodec/utils.c
> > > > index 52e0d92..b35fabc 100644
> > > > --- a/libavcodec/utils.c
> > > > +++ b/libavcodec/utils.c
> > > > @@ -2738,6 +2738,7 @@ static int do_decode(AVCodecContext *avctx,
> > > > AVPacket *pkt)
> > > > avctx->internal->draining_done = 1;
> > > >
> > > > if (ret >= pkt->size) {
> > > > + av_assert0(ret == pkt->size);
> > > > av_packet_unref(avctx->internal->buffer_pkt);
> > > > } else {
> > > > int consumed = ret;
> > >
> > > Basically all code using the "old" API expects that the decoder can
> > > read beyond the buffer (making use of input padding I suppose). So I
> > > think this is expected.
> >
> > iam not aware of any decoder that would return such a overread size
> > also to double check this yesterday i tested this with a bunch of
> > fuzzed files before posting the patch and failed to find anything that
> > triggers the assert
> >
> > [...]
>
> I'm talking about code like this:
>
> ret = FFMIN(ret, pkt->size); /* guard against bogus return values */
> pkt->data += ret;
> pkt->size -= ret;
>
> (currently found in ffprobe)
>
> Checks like this are all over the place.
>
> If you're confident that these checks are unnecessary and that
> avcodec_decode_audio4 should never return a larger value than the
> packet size, the assert should be added to avcodec_decode_audio4.
>
> Why do you want to add it specifically to do_decode?just saw the >= check in it and felt that it shouls never be > patch posted which adds it to avcodec_decode_audio4 [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB Those who are best at talking, realize last or never when they are wrong.
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