Re: [FFmpeg-devel] [PATCH 13/13] avformat/flvdec: support all multi-track modes

[Timo Rothenpieler <timo@rothenpieler.org>]

On 22.05.2024 02:02, Michael Niedermayer wrote:
> On Tue, May 21, 2024 at 11:02:22AM +0200, Timo Rothenpieler wrote:
>> ---
>>   libavformat/flvdec.c | 570 +++++++++++++++++++++++--------------------
>>   1 file changed, 306 insertions(+), 264 deletions(-)
> 
> infinite loops
> 
> [flv @ 0x555e803d2940] Video codec (0) is not implemented. Update your FFmpeg version to the newest one from Git. If the problem still occurs, it means that your file has a feature which has not been implemented.
> [flv @ 0x555e803d2940] If you want to help, upload a sample of this file to https://streams.videolan.org/upload/ and contact the ffmpeg-devel mailing list. (ffmpeg-devel@ffmpeg.org)
> [flv @ 0x555e803d2940] Video codec (0) is not implemented. Update your FFmpeg version to the newest one from Git. If the problem still occurs, it means that your file has a feature which has not been implemented.
> [flv @ 0x555e803d2940] If you want to help, upload a sample of this file to https://streams.videolan.org/upload/ and contact the ffmpeg-devel mailing list. (ffmpeg-devel@ffmpeg.org)
> [flv @ 0x555e803d2940] Video codec (0) is not implemented. Update your FFmpeg version to the newest one from Git. If the problem still occurs, it means that your file has a feature which has not been implemented.
> [flv @ 0x555e803d2940] If you want to help, upload a sample of this file to https://streams.videolan.org/upload/ and contact the ffmpeg-devel mailing list. (ffmpeg-devel@ffmpeg.org)
> [flv @ 0x555e803d2940] Video codec (0) is not implemented. Update your FFmpeg version to the newest one from Git. If the problem still occurs, it means that your file has a feature which has not been implemented.
> [flv @ 0x555e803d2940] If you want to help, upload a sample of this file to https://streams.videolan.org/upload/ and contact the ffmpeg-devel mailing list. (ffmpeg-devel@ffmpeg.org)
> [flv @ 0x555e803d2940] Video codec (0) is not implemented. Update your FFmpeg version to the newest one from Git. If the problem still occurs, it means that your file has a feature which has not been implemented.
> [flv @ 0x555e803d2940] If you want to help, upload a sample of this file to https://streams.videolan.org/upload/ and contact the ffmpeg-devel mailing list. (ffmpeg-devel@ffmpeg.org)
> [flv @ 0x555e803d2940] Video codec (0) is not implemented. Update your FFmpeg version to the newest one from Git. If the problem still occurs, it means that your file has a feature which has not been implemented.
> [flv @ 0x555e803d2940] If you want to help, upload a sample of this file to https://streams.videolan.org/upload/ and contact the ffmpeg-devel mailing list. (ffmpeg-devel@ffmpeg.org)
> [flv @ 0x555e803d2940] Video codec (0) is not implemented. Update your FFmpeg version to the newest one from Git. If the problem still occurs, it means that your file has a feature which has not been implemented.
> [flv @ 0x555e803d2940] If you want to help, upload a sample of this file to https://streams.videolan.org/upload/ and contact the ffmpeg-devel mailing list. (ffmpeg-devel@ffmpeg.org)
> [flv @ 0x555e803d2940] Video codec (0) is not implemented. Update your FFmpeg version to the newest one from Git. If the problem still occurs, it means that your file has a feature which has not been implemented.
> [flv @ 0x555e803d2940] If you want to help, upload a sample of this file to https://streams.videolan.org/upload/ and contact the ffmpeg-devel mailing list. (ffmpeg-devel@ffmpeg.org)
> [flv @ 0x555e803d2940] Video codec (0) is not implemented. Update your FFmpeg version to the newest one from Git. If the problem still occurs, it means that your file has a feature which has not been implemented.
> [flv @ 0x555e803d2940] If you want to help, upload a sample of this file to https://streams.videolan.org/upload/ and contact the ffmpeg-devel mailing list. (ffmpeg-devel@ffmpeg.org)
> [flv @ 0x555e803d2940] Video codec (0) is not implemented. Update your FFmpeg version to the newest one from Git. If the problem still occurs, it means that your file has a feature which has not been implemented.
> [flv @ 0x555e803d2940] If you want to help, upload a sample of this file to https://streams.videolan.org/upload/ and contact the ffmpeg-devel mailing list. (ffmpeg-devel@ffmpeg.org)
> [flv @ 0x555e803d2940] Video codec (0) is not implemented. Update your FFmpeg version to the newest one from Git. If the problem still occurs, it means that your file has a feature which has not been implemented.
> [flv @ 0x555e803d2940] If you want to help, upload a sample of this file to https://streams.videolan.org/upload/ and contact the ffmpeg-devel mailing list. (ffmpeg-devel@ffmpeg.org)
> [flv @ 0x555e803d2940] Video codec (0) is not implemented. Update your FFmpeg version to the newest one from Git. If the problem still occurs, it means that your file has a feature which has not been implemented.
> [flv @ 0x555e803d2940] If you want to help, upload a sample of this file to https://streams.videolan.org/upload/ and contact the ffmpeg-devel mailing list. (ffmpeg-devel@ffmpeg.org)
> CReceived > 3 system signals, hard exiting

Hm, what's happening here is that the sample has a packet which has an 
enormous size value, but obviously not actually half a million of tracks.

It's also not technically an infinite loop, but slowly counting down an 
enormous size.

Since eof is not checked anywhere, it happily keeps doing that.
There was also no check for size < 0 anywhere, so it over-reading and 
setting size to a negative value would make it run even longer.

Added both sanity checks for over-reading the size, and also eof in the 
middle of reading in the loop.
That fixed the issue for me.

Will send v2 shortly.
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