[FFmpeg-devel] libavcodec/als: remove check for predictor order of a block

[Umair Khan]

Hi,

On Fri, Oct 20, 2017 at 1:44 AM, Ronald S. Bultje <rsbultje at gmail.com> wrote:
>
> Hi,
>
> On Thu, Oct 19, 2017 at 4:03 PM, Umair Khan <omerjerk at gmail.com> wrote:
>
> > I tried decoding the file in both the cases and I don't see any
> > address related error in the console while decoding. Following is the
> > output after I apply the patch :-
> >
> [..]
>
> > Is there something which I'm missing?
> >
>
> You need to run under valgrind or compile with address sanitizer support:
> configure --toolchain=gcc-asan or --toolchain=clang-asan, depending on the
> name of clang on your system.

Thanks for the help. I was finally able to reproduce the error.

I have been trying to debug this heap-buffer-overflow error for some
days. I have finally found the source of the issue at least.

https://github.com/FFmpeg/FFmpeg/blob/master/libavcodec/alsdec.c#L934

raw_samples pointer is overflowing inside that loop. I haven't thought
of a proper fix for this yet. I'll look at the documentation to
understand the logic first.

However, in case someone (Thilo?) already has some idea on fixing it,
that'd be great.

Thanks,
Umair