[FFmpeg-devel] [PATCH] lavc/golomb: Fix UE golomb overwrite issue.

[Jun Zhao]

On 2017/5/29 7:40, Michael Niedermayer wrote:
> On Fri, May 26, 2017 at 09:19:09AM +0800, Jun Zhao wrote:
>>  golomb.h |    5 ++++-
>>  1 file changed, 4 insertions(+), 1 deletion(-)
>> 228c7180856b65d095dd0b8d59f3d3ff4f65774a  0001-lavc-golomb-Fix-UE-golomb-overwrite-issue.patch
>> From eabcbf3d41e83f24623e6195d4a0ff86e4d95a80 Mon Sep 17 00:00:00 2001
>> From: Jun Zhao <jun.zhao at intel.com>
>> Date: Fri, 26 May 2017 09:02:29 +0800
>> Subject: [PATCH] lavc/golomb: Fix UE golomb overwrite issue.
>>
>> put_bits just support write up to 31 bits, when write 32 bit in
>> put_bits, it's will overwrite the bit buffer, because the default
>> assert level is 0, the av_assert2(n <= 31 && value < (1U << n))
>> in put_bits can not be trigger runtime.
>>
>> Signed-off-by: Jun Zhao <jun.zhao at intel.com>
>> ---
>>  libavcodec/golomb.h | 5 ++++-
>>  1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/libavcodec/golomb.h b/libavcodec/golomb.h
>> index 0833aff468..2c5a969ac1 100644
>> --- a/libavcodec/golomb.h
>> +++ b/libavcodec/golomb.h
>> @@ -468,7 +468,10 @@ static inline void set_ue_golomb(PutBitContext *pb, int i)
>>          put_bits(pb, ff_ue_golomb_len[i], i + 1);
>>      else {
>>          int e = av_log2(i + 1);
>> -        put_bits(pb, 2 * e + 1, i + 1);
>> +        if (e < 16)
>> +            put_bits(pb, 2 * e + 1, i + 1);
>> +        else
>> +            put_bits32(pb, i + 1);
> 
> this is wrong
> 
> if e is 16 or larger the length is 33 bits or longer its never
> 32
> 

Yes, this is a wrong fix, how about add set_ue_golomb_long()/ set_ue_golomb_64() for this case ? 

> [...]
> 
> 
> 
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