Re: [FFmpeg-devel] [PATCH] Check codec_whitelist before reinitializing AVCtx.priv_data.

[Dale Curtis <dalecurtis@chromium.org>]

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On Wed, Jul 31, 2024 at 2:29 PM Dale Curtis <dalecurtis@chromium.org> wrote:

> On Wed, Jul 31, 2024 at 2:10 PM Dale Curtis <dalecurtis@chromium.org>
> wrote:
>
>> On Wed, Jul 31, 2024 at 4:32 AM Anton Khirnov <anton@khirnov.net> wrote:
>>
>>> Quoting Dale Curtis (2024-07-31 01:14:13)
>>> > I realized there are a couple more allocations that can be skipped here
>>> > when a codec is not on the allow list. Here's the updated patch.
>>> >
>>> > - dale
>>> >
>>> > On Mon, Jul 29, 2024 at 10:19 AM Dale Curtis <dalecurtis@chromium.org>
>>> > wrote:
>>> >
>>> > > This ensures that if a codec isn't on codec_whitelist, its VUI
>>> > > information can still be populated during find_stream_info()
>>> > > via parsers.
>>> > >
>>> > > Signed-off-by: Dale Curtis <dalecurtis@chromium.org>
>>> > > ---
>>> > >  libavcodec/avcodec.c | 12 ++++++------
>>> > >  1 file changed, 6 insertions(+), 6 deletions(-)
>>> > >
>>> > >
>>> >
>>> > From f87042d77d13c4c45f4b800146dc16347c1007d4 Mon Sep 17 00:00:00 2001
>>> > From: Dale Curtis <dalecurtis@chromium.org>
>>> > Date: Tue, 30 Jul 2024 23:12:21 +0000
>>> > Subject: [PATCH] Check codec_whitelist before reinitializing
>>> AVCtx.priv_data.
>>> >
>>> > This ensures that if a codec isn't on codec_whitelist, its VUI
>>> > information can still be populated during find_stream_info()
>>> > via parsers.
>>>
>>> Can you elaborate on this?
>>>
>>
>> The current code reinitializes the private data structures then checks
>> the whitelist. If the private data section had already been filled out, it
>> ends up being overwritten causing find_stream_info to drop side channel
>> data.
>>
>>
>>> >
>>> > Signed-off-by: Dale Curtis <dalecurtis@chromium.org>
>>> > ---
>>> >  libavcodec/avcodec.c | 11 +++++------
>>> >  1 file changed, 5 insertions(+), 6 deletions(-)
>>> >
>>> > diff --git a/libavcodec/avcodec.c b/libavcodec/avcodec.c
>>> > index 214dca4566..1f9b3eb360 100644
>>> > --- a/libavcodec/avcodec.c
>>> > +++ b/libavcodec/avcodec.c
>>> > @@ -174,6 +174,11 @@ int attribute_align_arg
>>> avcodec_open2(AVCodecContext *avctx, const AVCodec *code
>>> >      if (avctx->extradata_size < 0 || avctx->extradata_size >=
>>> FF_MAX_EXTRADATA_SIZE)
>>> >          return AVERROR(EINVAL);
>>> >
>>> > +    if (avctx->codec_whitelist && av_match_list(codec->name,
>>> avctx->codec_whitelist, ',') <= 0) {
>>> > +        av_log(avctx, AV_LOG_ERROR, "Codec (%s) not on whitelist
>>> \'%s\'\n", codec->name, avctx->codec_whitelist);
>>> > +        return AVERROR(EINVAL);
>>> > +    }
>>>
>>> I think this will break the case where the whitelist is provided in the
>>> options dictionary, as it's not applied yet at this point.
>>>
>>
>> I just copied the existing code a few lines up, so it seems ancillary to
>> this patch, but I can fix it in this one too if you want.
>>
>
> Nevermind, I see what you're saying -- yes this does break that case.
> Thanks for catching. I'll send a fix shortly.
>

Fixed. Thanks.


>
>
>>
>>
>>>
>>> --
>>> Anton Khirnov
>>> _______________________________________________
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>>> ffmpeg-devel@ffmpeg.org
>>> https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>>>
>>> To unsubscribe, visit link above, or email
>>> ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".
>>>
>>

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