[FFmpeg-devel] [PATCH 1/6] avcodec/qsvenc: Fix leak and crash when encoding H.264 due to A53_CC

[Andreas Rheinhardt]

Xiang, Haihao:
> On Sun, 2021-09-26 at 08:32 +0200, Andreas Rheinhardt wrote:
>> Since commit 3bbe0c210b05fc6fbd7b1d4bbd8479db7f2cf957, the Payloads
>> array of every QSVFrame leaks as soon as the frame is reused;
>> the leak is small and not very noticeable, but if there is an attempt
>> to use said array the ensuing crash is much more noticeable.
>> This happens when encoding H.264 with A53 CC side data.
>>
>> Furthermore, if said array can not be allocated at all, an AVFrame
>> leaks.
>>
>> Fix all of this by not allocating the array separately at all; put it
>> in QSVFrame instead and restore the Payloads array upon reusing the
>> frame.
>>
>> Finally, use av_freep() instead of av_free() to free the payload
>> entries.
>>
>> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at outlook.com>
>> ---
>>  libavcodec/qsv_internal.h |  2 ++
>>  libavcodec/qsvenc.c       | 10 +++-------
>>  2 files changed, 5 insertions(+), 7 deletions(-)
>>
>> diff --git a/libavcodec/qsv_internal.h b/libavcodec/qsv_internal.h
>> index 8090b748b3..fe9d5319c4 100644
>> --- a/libavcodec/qsv_internal.h
>> +++ b/libavcodec/qsv_internal.h
>> @@ -76,6 +76,8 @@ typedef struct QSVFrame {
>>      mfxExtDecodedFrameInfo dec_info;
>>      mfxExtBuffer *ext_param;
>>  
>> +    mfxPayload *payloads[QSV_MAX_ENC_PAYLOAD]; ///< used for enc_ctrl.Payload
>> +
>>      int queued;
>>      int used;
>>  
>> diff --git a/libavcodec/qsvenc.c b/libavcodec/qsvenc.c
>> index 06f55604b5..66f79bb021 100644
>> --- a/libavcodec/qsvenc.c
>> +++ b/libavcodec/qsvenc.c
>> @@ -1259,7 +1259,7 @@ static void free_encoder_ctrl_payloads(mfxEncodeCtrl*
>> enc_ctrl)
>>      if (enc_ctrl) {
>>          int i;
>>          for (i = 0; i < enc_ctrl->NumPayload && i < QSV_MAX_ENC_PAYLOAD; i++)
>> {
>> -            av_free(enc_ctrl->Payload[i]);
>> +            av_freep(&enc_ctrl->Payload[i]);
>>          }
>>          enc_ctrl->NumPayload = 0;
>>      }
>> @@ -1273,6 +1273,7 @@ static void clear_unused_frames(QSVEncContext *q)
>>              free_encoder_ctrl_payloads(&cur->enc_ctrl);
>>              //do not reuse enc_ctrl from previous frame
>>              memset(&cur->enc_ctrl, 0, sizeof(cur->enc_ctrl));
>> +            cur->enc_ctrl.Payload = cur->payloads;
>>              if (cur->frame->format == AV_PIX_FMT_QSV) {
>>                  av_frame_unref(cur->frame);
>>              }
>> @@ -1309,11 +1310,7 @@ static int get_free_frame(QSVEncContext *q, QSVFrame
>> **f)
>>          av_freep(&frame);
>>          return AVERROR(ENOMEM);
>>      }
>> -    frame->enc_ctrl.Payload = av_mallocz(sizeof(mfxPayload*) *
>> QSV_MAX_ENC_PAYLOAD);
>> -    if (!frame->enc_ctrl.Payload) {
>> -        av_freep(&frame);
>> -        return AVERROR(ENOMEM);
>> -    }
>> +    frame->enc_ctrl.Payload = frame->payloads;
>>      *last = frame;
>>  
>>      *f = frame;
>> @@ -1615,7 +1612,6 @@ int ff_qsv_enc_close(AVCodecContext *avctx,
>> QSVEncContext *q)
>>      while (cur) {
>>          q->work_frames = cur->next;
>>          av_frame_free(&cur->frame);
>> -        av_free(cur->enc_ctrl.Payload);
>>          av_freep(&cur);
>>          cur = q->work_frames;
>>      }
> 
> I'm sorry commit 3bbe0c2 caused a regression, your patch looks good to me.
> 

Thanks for the review. Here is a sample that allows to reproduce the
crash: http://streams.videolan.org/streams/ts/CC/NewsStream-608-ac3.ts
in case you haven't already have one.

- Andreas