Re: [FFmpeg-devel] [PATCH] avdevice/lavfi: fix crash on unconnected outpads

From: Paul B Mahol <onemda@gmail.com>
To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org>
Cc: metamuffin <metamuffin@disroot.org>
Subject: Re: [FFmpeg-devel] [PATCH] avdevice/lavfi: fix crash on unconnected outpads
Date: Thu, 1 Jun 2023 23:40:14 +0200
Message-ID: <CAPYw7P752898qngvdNd0Ga+9hyh0RXmtty0eCLcOWhr2Ssu36g@mail.gmail.com> (raw)
In-Reply-To: <20230601101336.24053-1-metamuffin@disroot.org>

On Thu, Jun 1, 2023 at 12:14 PM metamuffin <metamuffin@disroot.org> wrote:

> Nameless outpads would cause an invocation to sscanf with NULL.
> Example: ffmpeg -f lavfi -i 'nullsrc;nullsrc' -
> Changed to throwing an error instead.
>

See:

https://git.videolan.org/?p=ffmpeg.git;a=commit;h=5ce76506de1a7fbaf91af47a925d5ecfe13ae59c

Perhaps needs backporting to first introduction.

> ---
>  libavdevice/lavfi.c | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/libavdevice/lavfi.c b/libavdevice/lavfi.c
> index 9c1fcf334b..21f33ade0e 100644
> --- a/libavdevice/lavfi.c
> +++ b/libavdevice/lavfi.c
> @@ -174,6 +174,11 @@ av_cold static int lavfi_read_header(AVFormatContext
> *avctx)
>       * create a mapping between them and the streams */
>      for (i = 0, inout = output_links; inout; i++, inout = inout->next) {
>          int stream_idx = 0, suffix = 0, use_subcc = 0;
> +        if (!inout->name) {
> +            av_log(avctx,  AV_LOG_ERROR,
> +                   "Filtergraph has nameless outpads\n");
> +            FAIL(AVERROR(EINVAL));
> +        }
>          sscanf(inout->name, "out%n%d%n", &suffix, &stream_idx, &suffix);
>          if (!suffix) {
>              av_log(avctx,  AV_LOG_ERROR,
> --
> 2.40.1
>
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