diff mbox series

[FFmpeg-devel] lavf/mxfdec: Limit score for strangely cut files

Message ID CAB0OVGqiJX-CqPz=AA5EK0TwtTzuHYXDQpy3OvQJgV_wpbrXGg@mail.gmail.com
State Accepted
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Series [FFmpeg-devel] lavf/mxfdec: Limit score for strangely cut files | expand

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Commit Message

Carl Eugen Hoyos Aug. 24, 2020, 7:42 p.m. UTC 
Hi!

Attached patch fixes ticket #8846, the sample there is both a mov and
an mxf file.
It is not entirely clear to me if the sample was only made to annoy us
but the content looks real.

An alternative may be to check the extension if the score is equal but
I don't really like that either.

Other solutions welcome, Carl Eugen
Subject: [PATCH] lavf/mxfdec: Limit score for strangely cut files.

Only return AVPROBE_SCORE_MAX if the header partition pack key is at the
start of the file.
Fixes ticket #8846.
---
 libavformat/mxfdec.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Tomas Härdin Aug. 24, 2020, 10:48 p.m. UTC | #1 
mån 2020-08-24 klockan 21:42 +0200 skrev Carl Eugen Hoyos:
> Hi!
> 
> Attached patch fixes ticket #8846, the sample there is both a mov and
> an mxf file.
> It is not entirely clear to me if the sample was only made to annoy us
> but the content looks real.
> 
> An alternative may be to check the extension if the score is equal but
> I don't really like that either.

The file is a polyglot, yes. The run-in feature in MXF exists to be
able to add extra metadata and other MXF features while maintaining
backward compatibility. And to be annoying.

> Subject: [PATCH] lavf/mxfdec: Limit score for strangely cut files.

I'd reword this to "lavf/mxfdec: Limit score for files with run-in"

> @@ -3615,7 +3615,7 @@ static int mxf_probe(const AVProbeData *p) {
>                  AV_RN32(bufp+ 4) == AV_RN32(mxf_header_partition_pack_key+ 4) &&
>                  AV_RN32(bufp+ 8) == AV_RN32(mxf_header_partition_pack_key+ 8) &&
>                  AV_RN16(bufp+12) == AV_RN16(mxf_header_partition_pack_key+12))
> -                return AVPROBE_SCORE_MAX;
> +                return bufp - p->buf ? AVPROBE_SCORE_MAX - 1 : AVPROBE_SCORE_MAX;

bufp != p->buf would be more readable. Else this does the same thing as
a patch I was just working on, so the logic is OK.

/Tomas
Carl Eugen Hoyos Aug. 24, 2020, 11:06 p.m. UTC | #2 
Am Di., 25. Aug. 2020 um 00:48 Uhr schrieb Tomas Härdin <tjoppen@acc.umu.se>:
>
> mån 2020-08-24 klockan 21:42 +0200 skrev Carl Eugen Hoyos:
> > Hi!
> >
> > Attached patch fixes ticket #8846, the sample there is both a mov and
> > an mxf file.
> > It is not entirely clear to me if the sample was only made to annoy us
> > but the content looks real.
> >
> > An alternative may be to check the extension if the score is equal but
> > I don't really like that either.
>
> The file is a polyglot, yes. The run-in feature in MXF exists to be
> able to add extra metadata and other MXF features while maintaining
> backward compatibility. And to be annoying.

The file does not play here with -f mxf...

> > Subject: [PATCH] lavf/mxfdec: Limit score for strangely cut files.
>
> I'd reword this to "lavf/mxfdec: Limit score for files with run-in"
>
> > @@ -3615,7 +3615,7 @@ static int mxf_probe(const AVProbeData *p) {
> >                  AV_RN32(bufp+ 4) == AV_RN32(mxf_header_partition_pack_key+ 4) &&
> >                  AV_RN32(bufp+ 8) == AV_RN32(mxf_header_partition_pack_key+ 8) &&
> >                  AV_RN16(bufp+12) == AV_RN16(mxf_header_partition_pack_key+12))
> > -                return AVPROBE_SCORE_MAX;
> > +                return bufp - p->buf ? AVPROBE_SCORE_MAX - 1 : AVPROBE_SCORE_MAX;
>
> bufp != p->buf would be more readable. Else this does the same thing as
> a patch I was just working on, so the logic is OK.

Patch applied.

Thank you, Carl Eugen
diff mbox series

Patch

diff --git a/libavformat/mxfdec.c b/libavformat/mxfdec.c
index 4b56984b77..14b430a8d4 100644
--- a/libavformat/mxfdec.c
+++ b/libavformat/mxfdec.c
@@ -3615,7 +3615,7 @@  static int mxf_probe(const AVProbeData *p) {
                 AV_RN32(bufp+ 4) == AV_RN32(mxf_header_partition_pack_key+ 4) &&
                 AV_RN32(bufp+ 8) == AV_RN32(mxf_header_partition_pack_key+ 8) &&
                 AV_RN16(bufp+12) == AV_RN16(mxf_header_partition_pack_key+12))
-                return AVPROBE_SCORE_MAX;
+                return bufp - p->buf ? AVPROBE_SCORE_MAX - 1 : AVPROBE_SCORE_MAX;
             bufp ++;
         } else
             bufp += 10;