[FFmpeg-devel] [PATCH 1/8] avutil/mem: Handle fast allocations near UINT_MAX properly

[Anton Khirnov]

Quoting Andreas Rheinhardt (2022-07-06 15:08:05)
> Anton Khirnov:
> > Quoting Andreas Rheinhardt (2022-07-05 22:09:37)
> >> av_fast_realloc and av_fast_mallocz? store the size of
> >> the objects they allocate in an unsigned. Yet they overallocate
> >> and currently they can allocate more than UINT_MAX bytes
> >> in case a user has requested a size of about UINT_MAX * 16 / 17
> >> or more if SIZE_MAX > UINT_MAX. In this case it is impossible
> >> to store the true size of the buffer via the unsigned*;
> >> future requests are likely to use the (re)allocation codepath
> >> even if the buffer is actually large enough because of
> >> the incorrect size.
> >>
> >> Fix this by ensuring that the actually allocated size
> >> always fits into an unsigned. (This entails erroring out
> >> in case the user requested more than UINT_MAX.)
> > 
> > I really dislike this av_fast_* naming.
> > 
> > Given that all these functions use unsigned int for something that
> > should really be size_t, how about we deprecate them all and replace
> > with something that has a sane naming convention and uses proper types?
> > 
> 
> What name do you suggest?

I suggested av_?alloc*_reuse() in a recent thread, since those function
are "fast" by reusing the buffer when possible.

> And what's your opinion of the actual patch?

Seems straightforwardly ok.

-- 
Anton Khirnov