[FFmpeg-devel] [PATCH v4] fftools/opts: Avoid crash when opts could not be allocated

[Andreas Rheinhardt]

Yu Yang:
> If 'opts' could not be allocated, exiting the program to avoid crash when release it. 
> Before setup_find_stream_info_opts(), checking 'orig_nb_streams' is > 0.
> 
> Reported-by: TOTE Robot <oslab at tsinghua.edu.cn>
> Signed-off-by: Yu Yang <young_chelsea at 163.com>
> ---
>  fftools/cmdutils.c   | 4 +---
>  fftools/cmdutils.h   | 4 ++--
>  fftools/ffmpeg_opt.c | 5 +++--
>  3 files changed, 6 insertions(+), 7 deletions(-)
> 
> diff --git a/fftools/cmdutils.c b/fftools/cmdutils.c
> index 3c8e5a82cd..4b977f16e5 100644
> --- a/fftools/cmdutils.c
> +++ b/fftools/cmdutils.c
> @@ -2181,13 +2181,11 @@ AVDictionary **setup_find_stream_info_opts(AVFormatContext *s,
>      int i;
>      AVDictionary **opts;
>  
> -    if (!s->nb_streams)
> -        return NULL;

Moving this check to the caller makes this a bit uglier and misses the
point that this function is also called from ffplay and ffprobe (where
they will cause unnecessary allocations of arrays with zero entries).

>      opts = av_calloc(s->nb_streams, sizeof(*opts));
>      if (!opts) {
>          av_log(NULL, AV_LOG_ERROR,
>                 "Could not alloc memory for stream options.\n");
> -        return NULL;
> +        exit_program(1);
>      }
>      for (i = 0; i < s->nb_streams; i++)
>          opts[i] = filter_codec_opts(codec_opts, s->streams[i]->codecpar->codec_id,
> diff --git a/fftools/cmdutils.h b/fftools/cmdutils.h
> index 82cda208be..50eed9b13a 100644
> --- a/fftools/cmdutils.h
> +++ b/fftools/cmdutils.h
> @@ -430,8 +430,8 @@ AVDictionary *filter_codec_opts(AVDictionary *opts, enum AVCodecID codec_id,
>   * Each dictionary will contain the options from codec_opts which can
>   * be applied to the corresponding stream codec context.
>   *
> - * @return pointer to the created array of dictionaries, NULL if it
> - * cannot be created
> + * @return pointer to the created array of dictionaries.
> + * Calls exit() on failure.
>   */
>  AVDictionary **setup_find_stream_info_opts(AVFormatContext *s,
>                                             AVDictionary *codec_opts);
> diff --git a/fftools/ffmpeg_opt.c b/fftools/ffmpeg_opt.c
> index a703798586..aac40acb9f 100644
> --- a/fftools/ffmpeg_opt.c
> +++ b/fftools/ffmpeg_opt.c
> @@ -1191,9 +1191,10 @@ static int open_input_file(OptionsContext *o, const char *filename)
>          choose_decoder(o, ic, ic->streams[i]);
>  
>      if (find_stream_info) {
> -        AVDictionary **opts = setup_find_stream_info_opts(ic, o->g->codec_opts);
> +        AVDictionary **opts = NULL;
>          int orig_nb_streams = ic->nb_streams;
> -
> +        if (orig_nb_streams > 0)
> +            opts = setup_find_stream_info_opts(ic, o->g->codec_opts);
>          /* If not enough info to get the stream parameters, we decode the
>             first frames to get it. (used in mpeg case for example) */
>          ret = avformat_find_stream_info(ic, opts);
>