Vitor Sessak <[email protected]> writes:

> On 02/29/2012 04:28 PM, Janne Grunau wrote:
>> On 2012-02-26 09:52:44 +0100, Vitor Sessak wrote:
>>> ---
>>>   libavcodec/ra144dec.c |    2 ++
>>>   libavcodec/ra288.c    |    2 ++
>>>   libavcodec/sipr.c     |    2 ++
>>>   libavcodec/twinvq.c   |    2 ++
>>>   4 files changed, 8 insertions(+), 0 deletions(-)
>>
>> Why?
>>
>> Have you proofed that each of the decoder can't overread?
>
> Of course I did. I concede didn't do it with the AMRNB in my first
> patch. I was almost sure I saw the check when I reviewed it, but I was
> wrong.

[...]

>> I would say the decoders are not important enough and speed penalty
>> for audio doesn't matter enough to disable the safe bitstream reader.
>
> How hard is it to check a single constant value correctly? What is the
> use of the safe bitstream reader if the check is done right?

There's much more to it than that.  Almost anything using
variable-length codes will need more than a simple packet size check, or
a damaged/malicious bitstream may cause over-reads.

-- 
Måns Rullgård
[email protected]
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