Quoting Michael Niedermayer (2023-10-01 00:28:56)
> On Sat, Sep 30, 2023 at 10:18:38PM +0200, Anton Khirnov wrote:
> > Quoting Michael Niedermayer (2023-09-30 16:31:43)
> > > On Sat, Sep 30, 2023 at 04:04:03PM +0200, Michael Niedermayer wrote:
> > > > On Sat, Sep 30, 2023 at 11:35:19AM +0200, Marton Balint wrote:
> > > > >
> > > > >
> > > > > On Sat, 30 Sep 2023, Michael Niedermayer wrote:
> > > > >
> > > > > > Fixes: signed integer overflow: 109817402400 * 301990077 cannot be
> > > > > > represented in type 'long long'
> > > > > > Fixes:
> > > > > > 51896/clusterfuzz-testcase-minimized-ffmpeg_dem_AVI_fuzzer-6706191715139584
> > > > > >
> > > > > > Found-by: continuous fuzzing process
> > > > > > https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> > > > > > Signed-off-by: Michael Niedermayer <mich...@niedermayer.cc>
> > > > > > ---
> > > > > > libavformat/avidec.c | 12 ++++++++++--
> > > > > > 1 file changed, 10 insertions(+), 2 deletions(-)
> > > > > >
> > > > > > diff --git a/libavformat/avidec.c b/libavformat/avidec.c
> > > > > > index 00bd7a98a9d..cfc693842b7 100644
> > > > > > --- a/libavformat/avidec.c
> > > > > > +++ b/libavformat/avidec.c
> > > > > > @@ -27,6 +27,7 @@
> > > > > > #include "libavutil/avstring.h"
> > > > > > #include "libavutil/opt.h"
> > > > > > #include "libavutil/dict.h"
> > > > > > +#include "libavutil/integer.h"
> > > > > > #include "libavutil/internal.h"
> > > > > > #include "libavutil/intreadwrite.h"
> > > > > > #include "libavutil/mathematics.h"
> > > > > > @@ -476,7 +477,7 @@ static int calculate_bitrate(AVFormatContext *s)
> > > > > > AVStream *st = s->streams[i];
> > > > > > FFStream *const sti = ffstream(st);
> > > > > > int64_t duration;
> > > > > > - int64_t bitrate;
> > > > > > + int64_t bitrate = 0;
> > > > > >
> > > > > > for (j = 0; j < sti->nb_index_entries; j++)
> > > > > > len += sti->index_entries[j].size;
> > > > > > @@ -484,7 +485,14 @@ static int calculate_bitrate(AVFormatContext
> > > > > > *s)
> > > > > > if (sti->nb_index_entries < 2 || st->codecpar->bit_rate > 0)
> > > > > > continue;
> > > > > > duration = sti->index_entries[j-1].timestamp -
> > > > > > sti->index_entries[0].timestamp;
> > > > > > - bitrate = av_rescale(8*len, st->time_base.den, duration *
> > > > > > st->time_base.num);
> > > > > > + if (INT64_MAX / duration >= st->time_base.num) {
> > > > > > + bitrate = av_rescale(8*len, st->time_base.den,
> > > > > > duration * st->time_base.num);
> > > > >
> > > > > Why not always use the AVInteger version? This is not performance
> > > > > sensitive
> > > > > as far as I see.
> > > >
> > > > We can, i will have to fix the rounding though so it matches
> > > > av_rescale()
> > >
> > > will apply this with just AVInteger and fixed rounding with my next push
> > > probably
> >
> > This seems MUCH less readable to me.
>
> we can add a av_rescale_2den()
Won't av_rescale_q(len, (AVRational){8, duration}, st->time_base)
achieve the same effect?
--
Anton Khirnov
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