[FFmpeg-devel] [PATCH] ARMovie/RPL demuxer rev4

[Michael Niedermayer]

On Sat, Mar 29, 2008 at 02:31:29AM +0100, Reimar D?ffinger wrote:
> On Sat, Mar 29, 2008 at 01:22:59AM +0000, M?ns Rullg?rd wrote:
> > "Eli Friedman" <eli.friedman at gmail.com> writes:
> > 
> > > On Fri, Mar 28, 2008 at 6:06 PM, M?ns Rullg?rd <mans at mansr.com> wrote:
> > >> "Eli Friedman" <eli.friedman at gmail.com> writes:
> > >>
> > >>  > On Fri, Mar 28, 2008 at 4:38 PM, Michael Niedermayer <michaelni at gmx.at> wrote:
> > >>  >> On Fri, Mar 28, 2008 at 04:13:02PM -0700, Eli Friedman wrote:
> > >>
> > >> >>  > +        if (offset >= 0xFFFFFFFFUL || video_size >= 0xFFFFFFFFUL ||
> > >>  >>  > +            audio_size >= 0xFFFFFFFFUL)
> > >>  >>  > +            error |= -1;
> > >>  >>
> > >>  >>  What exactly is this check good for?
> > >>  >
> > >>  > Overflow, so it doesn't silently accept 10000000000000 as an offset.
> > >>
> > >>  Quoting the C99 section on sscanf:
> > >>
> > >>   [...] if the result of the conversion cannot be represented in the
> > >>   object, the behavior is undefined.
> > >>
> > >>  This means that if the input contains a number too large for, in your
> > >>  case, a long, anything could be returned, including a seemingly
> > >>  sensible value.  Those checks are thus pointless.  If input validation
> > >>  at stage is a concern, don't use sscanf().
> > >
> > > Oh, hmm, okay.  I had assumed that all sscanf implementations would
> > > act like the glibc one and strtoul, which return 0xFFFFFFFF for
> > > out-of-range unsigned values.
> > 
> > You mean out-of-range unsigned 32-bit values.  You used the long type,
> > which is frequently 64 bits wide.
> 
> Which IMO is a really horrible idea, since that means the demuxer will
> behave differently on 32 and 64 bit systems.
> You could use one of the SCN?64 defines and uint64_t...

Yes, iam glad you found that issue in time, after that is fixed we will
finally be able to play all thouse >4gb ARMovie/RPL files which we have
been collecting. ;)

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

The misfortune of the wise is better than the prosperity of the fool.
-- Epicurus
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