[FFmpeg-devel] [PATCH 1/2] avcodec/cbs_h264: Automatically free SEI payload on error

[Mark Thompson]

On 11/09/2019 23:18, Andreas Rheinhardt wrote:
> If adding an SEI message to an access unit fails, said SEI message was
> not touched, so that the caller had to free any data associated with it
> that might need to be freed. But given that ff_cbs_h264_add_sei_message
> can simply call cbs_h264_free_sei_payload, one can easily free
> the content of the SEI payload.
> 
> This fixes a memleak when inserting a user data unregistered string for
> h264_metadata fails.
> 
> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at gmail.com>
> ---
>  libavcodec/cbs_h264.h  |  5 ++++-
>  libavcodec/cbs_h2645.c | 16 +++++++++++-----
>  2 files changed, 15 insertions(+), 6 deletions(-)
> 
> diff --git a/libavcodec/cbs_h264.h b/libavcodec/cbs_h264.h
> index b39e7480c9..9f7c2a0d30 100644
> --- a/libavcodec/cbs_h264.h
> +++ b/libavcodec/cbs_h264.h
> @@ -468,10 +468,13 @@ typedef struct CodedBitstreamH264Context {
>  
>  /**
>   * Add an SEI message to an access unit.
> + *
> + * On success, the payload will be owned by a unit in access_unit;
> + * on failure, the content of the payload will be freed.
>   */
>  int ff_cbs_h264_add_sei_message(CodedBitstreamContext *ctx,
>                                  CodedBitstreamFragment *access_unit,
> -                                const H264RawSEIPayload *payload);
> +                                H264RawSEIPayload *payload);
>  
>  /**
>   * Delete an SEI message from an access unit.
> diff --git a/libavcodec/cbs_h2645.c b/libavcodec/cbs_h2645.c
> index 8da8421e47..2dc261f7a5 100644
> --- a/libavcodec/cbs_h2645.c
> +++ b/libavcodec/cbs_h2645.c
> @@ -1586,7 +1586,7 @@ const CodedBitstreamType ff_cbs_type_h265 = {
>  
>  int ff_cbs_h264_add_sei_message(CodedBitstreamContext *ctx,
>                                  CodedBitstreamFragment *au,
> -                                const H264RawSEIPayload *payload)
> +                                H264RawSEIPayload *payload)
>  {
>      H264RawSEI *sei = NULL;
>      int err, i;
> @@ -1608,8 +1608,10 @@ int ff_cbs_h264_add_sei_message(CodedBitstreamContext *ctx,
>          AVBufferRef *sei_ref;
>  
>          sei = av_mallocz(sizeof(*sei));
> -        if (!sei)
> -            return AVERROR(ENOMEM);
> +        if (!sei) {
> +            err = AVERROR(ENOMEM);
> +            goto fail;
> +        }
>  
>          sei->nal_unit_header.nal_unit_type = H264_NAL_SEI;
>          sei->nal_unit_header.nal_ref_idc   = 0;
> @@ -1618,7 +1620,8 @@ int ff_cbs_h264_add_sei_message(CodedBitstreamContext *ctx,
>                                     &cbs_h264_free_sei, NULL, 0);
>          if (!sei_ref) {
>              av_freep(&sei);
> -            return AVERROR(ENOMEM);
> +            err = AVERROR(ENOMEM);
> +            goto fail;
>          }
>  
>          for (i = 0; i < au->nb_units; i++) {
> @@ -1631,13 +1634,16 @@ int ff_cbs_h264_add_sei_message(CodedBitstreamContext *ctx,
>                                           sei, sei_ref);
>          av_buffer_unref(&sei_ref);
>          if (err < 0)
> -            return err;
> +            goto fail;
>      }
>  
>      memcpy(&sei->payload[sei->payload_count], payload, sizeof(*payload));
>      ++sei->payload_count;
>  
>      return 0;
> +fail:
> +    cbs_h264_free_sei_payload(payload);
> +    return err;
>  }
>  
>  void ff_cbs_h264_delete_sei_message(CodedBitstreamContext *ctx,
> 

Hmm - this rather makes me think that the API to the function isn't the right one.

Still, it's only used in one place right now and it fixes the immediate problem.  So LGTM, applied.

Thanks,

- Mark