[FFmpeg-devel] [PATCH v1] avcodec/h2645_parse: fix for the realloc size

[Limin Wang]

On Mon, Sep 09, 2019 at 10:53:53PM -0300, James Almer wrote:
> On 9/9/2019 10:18 PM, lance.lmwang at gmail.com wrote:
> > From: Limin Wang <lance.lmwang at gmail.com>
> > 
> > Signed-off-by: Limin Wang <lance.lmwang at gmail.com>
> > ---
> >  libavcodec/h2645_parse.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/libavcodec/h2645_parse.c b/libavcodec/h2645_parse.c
> > index 307e8643e6..403acd2ee1 100644
> > --- a/libavcodec/h2645_parse.c
> > +++ b/libavcodec/h2645_parse.c
> > @@ -454,7 +454,7 @@ int ff_h2645_packet_split(H2645Packet *pkt, const uint8_t *buf, int length,
> >          }
> >  
> >          if (pkt->nals_allocated < pkt->nb_nals + 1) {
> > -            int new_size = pkt->nals_allocated + 1;
> > +            int new_size = pkt->nb_nals + 1;
> 
> No. nals_allocated and nb_nals are two purposely separate values in
> order to reuse the H2645Packet struct. One keeps track of the allocated
> size of the NAL buffer, whereas the other keeps track of the amount of
> NALs used by the current packet. That's why the check immediately above
> this line makes sure the amount of NALs in the current packet fit in the
> current size of the NAL buffer, and grows/reallocates it otherwise.

Thanks for the detail information about the two field. Below is my assumation 
as I haven't such sample to test such case.
Assuming nals_allocated is 1, nb_nals is 3, then the current code will reallocate
new_size with 2, But the following code will use the nb_nals to access pkt->nals, 
I'm not sure nals memory is allocated or not?
nal = &pkt->nals[pkt->nb_nals];


> 
> >              void *tmp = av_realloc_array(pkt->nals, new_size, sizeof(*pkt->nals));
> >  
> >              if (!tmp)
> > 
> 
> _______________________________________________
> ffmpeg-devel mailing list
> ffmpeg-devel at ffmpeg.org
> https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
> 
> To unsubscribe, visit link above, or email
> ffmpeg-devel-request at ffmpeg.org with subject "unsubscribe".