Re: [FFmpeg-devel] [PATCH 5/5] avcodec/hevc_mp4toannexb_bsf: Check that there is enough input left for nalu size

[Michael Niedermayer]

On Fri, Dec 13, 2019 at 12:24:04PM +0100, Andreas Rheinhardt wrote:
> On Fri, Dec 13, 2019 at 3:07 AM Michael Niedermayer <mich...@niedermayer.cc>
> wrote:
> 
> > No testcase
> >
> > Signed-off-by: Michael Niedermayer <mich...@niedermayer.cc>
> > ---
> >  libavcodec/hevc_mp4toannexb_bsf.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/libavcodec/hevc_mp4toannexb_bsf.c
> > b/libavcodec/hevc_mp4toannexb_bsf.c
> > index baa93628ed..e0d20a550c 100644
> > --- a/libavcodec/hevc_mp4toannexb_bsf.c
> > +++ b/libavcodec/hevc_mp4toannexb_bsf.c
> > @@ -152,7 +152,9 @@ static int hevc_mp4toannexb_filter(AVBSFContext *ctx,
> > AVPacket *out)
> >          extra_size    = add_extradata * ctx->par_out->extradata_size;
> >          got_irap     |= is_irap;
> >
> > -        if (FFMIN(INT_MAX, SIZE_MAX) < 4ULL + nalu_size + extra_size) {
> > +        if (FFMIN(INT_MAX, SIZE_MAX) < 4ULL + nalu_size + extra_size ||
> >
> 
> Up until now I thought that FFmpeg has some implicit assumptions: int
> having 32bit being one of them (the log2 functions depend on this). And I

yes, that was from POSIX


> also thought that size_t being able to hold all the values of an unsigned
> was one of these implicit assumptions, too. Am I wrong on this?

I was asking myself the same, and i couldnt really find anything where we
stated that previously so i added a FFMIN.


> 
> A testcase for the last condition is easy to produce by simply manipulating
> the size field of a NAL unit.

yes, do you think we should create such a testcase for this fix ?

thx

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