[FFmpeg-devel] [PATCH]lavc/frame_thread_encoder: Do not memcpy() from NULL

[Mark Thompson]

On 02/07/2019 10:44, Carl Eugen Hoyos wrote:
> Am Di., 2. Juli 2019 um 08:31 Uhr schrieb Reimar Döffinger
> <Reimar.Doeffinger at gmx.de>:
>>
>> On 01.07.2019, at 00:51, Carl Eugen Hoyos <ceffmpeg at gmail.com> wrote:
> 
>>> I believe attached patch fixes undefined behaviour and ticket #7981.
>>
>> Same here, I think it makes more sense to check the "size" instead of the pointer.
> 
> True, new patch attached.
> 
>> But I also suspect we might want to think of a way to not need all these explicit checks all over.
> 
> There are some places, but not so many afair.
> 
> Carl Eugen
> 
> 
> From 263adbc580ecbc67edbdc6d0f89e91a484bd520f Mon Sep 17 00:00:00 2001
> From: Carl Eugen Hoyos <ceffmpeg at gmail.com>
> Date: Tue, 2 Jul 2019 11:42:32 +0200
> Subject: [PATCH] lavc/frame_thread_encoder: Do not memcpy() from NULL.
> 
> Fixes ticket #7981.
> ---
>  libavcodec/frame_thread_encoder.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/libavcodec/frame_thread_encoder.c b/libavcodec/frame_thread_encoder.c
> index 55756c4c54..949bc69f81 100644
> --- a/libavcodec/frame_thread_encoder.c
> +++ b/libavcodec/frame_thread_encoder.c
> @@ -209,8 +209,9 @@ int ff_frame_thread_encoder_init(AVCodecContext *avctx, AVDictionary *options){
>              int ret = av_opt_copy(thread_avctx->priv_data, avctx->priv_data);
>              if (ret < 0)
>                  goto fail;
> -        } else
> +        } else if (avctx->codec->priv_data_size) {
>              memcpy(thread_avctx->priv_data, avctx->priv_data, avctx->codec->priv_data_size);
> +        }
>          thread_avctx->thread_count = 1;
>          thread_avctx->active_thread_type &= ~FF_THREAD_FRAME;
>  
> -- 
> 2.22.0
> 

This is a good idea anyway regardless of the outcome of the av_memcpy() discussion.  LGTM.

Thanks,

- Mark