[FFmpeg-devel] [PATCH] lavd/lavfi: fix two memleaks.

[Stefano Sabatini]

On date Sunday 2011-12-18 01:01:32 +0100, Stefano Sabatini encoded:
> On date Friday 2011-12-16 22:38:09 +0100, Michael Niedermayer encoded:
> > On Fri, Dec 16, 2011 at 09:54:52PM +0100, Nicolas George wrote:
> > > Le sextidi 26 frimaire, an CCXX, Michael Niedermayer a écrit :
> > > > this might lead to use after free in sink_buffer.c if iam not misssing
> > > > anything
> > >
> > > I looked into it before submitting, and I think that sink_buffer will not
> > > use it after init(), which is called by avfilter_graph_config. And valgrind
> > > did not show new errors after the new free.
> > 
> > My concern is that we pass a pointer into sink_buffer which keeps it
> > and uses it in an exported function (its query_formats() that gets
> > called by avfilter_graph_config())
> > and we free it outside while sink_buffer retains this now invalid
> > pointer.
> > 
> 
> > AFAIK nothing calls query_formats() again and
> > nothing uses that pointer except query_formats(). But i think it
> > would be better if this pointer was set to NULL once it becomes
> > unavailable or if it would be freed only once sink_buffer is freed
> 
> I agree with this.
> 
> In vsink_init() we have:
> 
> #if FF_API_OLD_VSINK_API
>         buf->pixel_fmts = (const enum PixelFormat *)opaque;
> #else
>         params = (AVBufferSinkParams *)opaque;
>         buf->pixel_fmts = params->pixel_fmts;
> #endif
> 
> so the passed opaque data is referenced in the buffersink context (and
> never freed). I suppose the safest approach is to require the caller
> to allocate the opaque data (like it is right now), and ask buffersink
> to free it (which is not doing, and leaking).

After more tinkering and supposing I'm not already sleeping: we should
copy the pix_fmts list in the buffersink, free the original list in
the lavfi device and free the copy in the buffersink uninit().

I'll try to write a patch for this tomorrow, but feel free to beat me
at it.
-- 
FFmpeg = Fantastic & Funny Most Philosophical Encoding/decoding God