[FFmpeg-devel] [PATCH 2/4] avcodec/avpacket: Perform fewer reallocations in repeated av_grow_packet()

[Michael Niedermayer]

On Mon, Dec 06, 2021 at 11:04:09AM +0100, Anton Khirnov wrote:
> Quoting Michael Niedermayer (2021-12-04 22:32:56)
> > Fixes: Timeout
> > Fixes: 41446/clusterfuzz-testcase-minimized-ffmpeg_dem_SAMI_fuzzer-4667644540747776
> > 
> > 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/avpacket.c | 7 ++++++-
> >  1 file changed, 6 insertions(+), 1 deletion(-)
> > 
> > diff --git a/libavcodec/avpacket.c b/libavcodec/avpacket.c
> > index d8d8fef3b9e..b10498bfc1d 100644
> > --- a/libavcodec/avpacket.c
> > +++ b/libavcodec/avpacket.c
> > @@ -142,7 +142,12 @@ int av_grow_packet(AVPacket *pkt, int grow_by)
> >  
> >          if (new_size + data_offset > pkt->buf->size ||
> >              !av_buffer_is_writable(pkt->buf)) {
> > -            int ret = av_buffer_realloc(&pkt->buf, new_size + data_offset);
> > +            int ret;
> > +
> > +            if (new_size + data_offset < INT_MAX - new_size/16)
> > +                new_size += new_size/16;
> > +
> > +            ret = av_buffer_realloc(&pkt->buf, new_size + data_offset);
> 
> This needs a comment, e.g.
> // allocate slightly more than requested to avoid excessive
> // reallocations

above comment added

thx

> 
> Flow control in this function is overly complicated as it is.

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

Those who are best at talking, realize last or never when they are wrong.
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