Re: [FFmpeg-devel] [PATCH 07/10] avformat/wavdec: sanity check channels and bps before using them for block_align

[Michael Niedermayer <michael@niedermayer.cc>]

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On Wed, Mar 27, 2024 at 10:42:31AM +0100, Anton Khirnov wrote:
> Quoting Michael Niedermayer (2024-03-26 01:11:48)
> > Fixes: 62276/clusterfuzz-testcase-minimized-ffmpeg_dem_W64_fuzzer-4704044498944000
> > Fixes: signed integer overflow: 520464 * 8224 cannot be represented in type 'int'
> > 
> > Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> > Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
> > ---
> >  libavformat/wavdec.c | 5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> > 
> > diff --git a/libavformat/wavdec.c b/libavformat/wavdec.c
> > index 668c8adc36b..89855670d9c 100644
> > --- a/libavformat/wavdec.c
> > +++ b/libavformat/wavdec.c
> > @@ -34,6 +34,7 @@
> >  #include "libavutil/log.h"
> >  #include "libavutil/mathematics.h"
> >  #include "libavutil/opt.h"
> > +#include "libavcodec/internal.h"
> >  #include "avformat.h"
> >  #include "avio.h"
> >  #include "avio_internal.h"
> > @@ -908,7 +909,9 @@ static int w64_read_header(AVFormatContext *s)
> >              if (ret < 0)
> >                  return ret;
> >              avio_skip(pb, FFALIGN(size, INT64_C(8)) - size);
> > -            if (st->codecpar->block_align) {
> > +            if (st->codecpar->block_align &&
> > +                st->codecpar->ch_layout.nb_channels < FF_SANE_NB_CHANNELS &&
> 
> I objected to this approach.

Maybe that was your intend but what you actually wrote and what i understood
was that you objected to adding a field to AVFormatContext
For reference:

    > is anyone against adding a max_channels field to AVFormatContext  or something
    > like that ?

    I am.

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

It is a danger to trust the dream we wish for rather than
the science we have, -- Dr. Kenneth Brown

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