[FFmpeg-devel] [PATCH] avcodec/alsdec: use correct variable when checking for overwrite

[Thilo Borgmann]

Am 30.06.17 um 19:34 schrieb Paul B Mahol:
> On 6/30/17, Thilo Borgmann <thilo.borgmann at mail.de> wrote:
>> Am 30.06.17 um 18:43 schrieb Paul B Mahol:
>>> Fixes #5297.
>>>
>>> Signed-off-by: Paul B Mahol <onemda at gmail.com>
>>> ---
>>>  libavcodec/alsdec.c | 4 ++--
>>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/libavcodec/alsdec.c b/libavcodec/alsdec.c
>>> index d95e30d..a925502 100644
>>> --- a/libavcodec/alsdec.c
>>> +++ b/libavcodec/alsdec.c
>>> @@ -705,8 +705,8 @@ static int read_var_block_data(ALSDecContext *ctx,
>>> ALSBlockData *bd)
>>>          } else {
>>>              *bd->opt_order = sconf->max_order;
>>>          }
>>> -        if (*bd->opt_order > bd->block_length) {
>>> -            *bd->opt_order = bd->block_length;
>>> +        if (*bd->opt_order > sconf->max_order) {
>>> +            *bd->opt_order = sconf->max_order;
>>>              av_log(avctx, AV_LOG_ERROR, "Predictor order too large.\n");
>>>              return AVERROR_INVALIDDATA;
>>>          }
>>
>>
>> This check will never fire because in all cases this check has already been
>> applied or opt_order is explicitly set to equal max_order. See code above.
>>
>> Paul, seriously, are you just trying to get me even more busy?
> 
> Does it fixes crash or not?

I assume you tested and it does for #5297. However, as I tried to outline, your
patch here is equal to remove this check alltogether and therefore does not fix
why it has been added.

-Thilo