[FFmpeg-devel] n4.4 release bug (?) on ffmpeg.c av_fifo_generic_read

[Đông Nguyễn]

ah I see, my bad, thanks for make it clear

Regards
Dong Nguyen


On Sun, Apr 18, 2021, 08:47 James Almer <jamrial at gmail.com> wrote:

> On 4/17/2021 10:16 PM, Đông Nguyễn wrote:
> > Hi,
> >
> > Not sure this is the correct place to post this, but I've noticed some
> > recent changes (n.4.4) on ffmpeg.c which seems suspicious to me.
> >
> > https://github.com/FFmpeg/FFmpeg/blob/n4.4/fftools/ffmpeg.c#L532-L535
>
> This one is in 4.3 too. Not sure why you think it was changed for 4.4.
>
> > https://github.com/FFmpeg/FFmpeg/blob/n4.4/fftools/ffmpeg.c#L614-L616
> >
> > IIRC, before these changes, av_fifo_generic_read operates on whole struct
> > of AVFrame and AVPacket, not sole pointer (which has only 8 bytes on
> 64bit
> > machine)
> >
> > After that, calling "free" on those pointers potentially causes malloc
> heap
> > crashes.
> >
> > Please correct me if I'm wrong. Thanks
>
> Both FIFOs effectively store pointers to dynamically allocated structs,
> and not entire structs. So reading sizeof(void*) worth of bytes is
> intended.
>
> >
> > Dong Nguyen
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>
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