[Ffmpeg-devel] [PATCH] fix jpegls unitialized data reading

[Michael Niedermayer]

Hi

On Sat, Dec 09, 2006 at 11:52:54PM +0100, Reimar D?ffinger wrote:
> Hello,
> On Sat, Dec 09, 2006 at 11:48:17PM +0100, Reimar D?ffinger wrote:
> > On Sat, Dec 09, 2006 at 11:29:57PM +0100, Reimar D?ffinger wrote:
> > > +    put_bits(&pb2, 16, 0);
> > >      flush_put_bits(&pb2);
> > >      /* do escape coding */
> > > -    size = put_bits_count(&pb2) >> 3;
> > > +    size = (put_bits_count(&pb2) >> 3) - 2;
> > 
> > Just initializing 8 extra bits instead of 16 is enough, because v ==
> > 0xff is not possible when we already hit the end before reading v
> > completely.
> > Actually that even means that 7 bits extra initialization would be
> > enough, but that would be complicate to compensate due to
> > flush_put_bits.
> > Of course, just a memset of buf2 to 0 right at the start works, too.
> 
> Sorry, yet another correction. init_get_bits should get the larger size,
> too, in case somebody adds thorough checking of get_bits limits e.g. for
> debugging purposes.

hmm what about align_put_bits() ?

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

I am the wisest man alive, for I know one thing, and that is that I know
nothing. -- Socrates