[FFmpeg-devel] [PATCH] avcodec/movtextenc: fix compile warning for type-limits

[Nuo Mi]

On Mon, Feb 15, 2021 at 2:02 AM Carl Eugen Hoyos <ceffmpeg at gmail.com> wrote:

> Am So., 14. Feb. 2021 um 18:57 Uhr schrieb Nuo Mi <nuomi2021 at gmail.com>:
>
> > >
> https://github.com/FFmpeg/FFmpeg/blob/21346672270ae723aa774a9c8b0749954a75b3df/libavcodec/movtextenc.c#L110
> > > > > > s->count * sizeof(*s->style_attributes) never > 32 bits.
> > >
> > > This is not correct afaict:
> > > The relevant line is 369 not 110, count is of type unsigned and if you
> > > multiply it with something >1, it can overflow.
> > >
> > You are right, the count is unsigned int, but
> >
> https://github.com/FFmpeg/FFmpeg/blob/21346672270ae723aa774a9c8b0749954a75b3df/libavcodec/movtextenc.c#L112
> > tells us the value never > 16 bits
>
> No, this is not correct:
> Line 112 does not know how often line 369 was called.
>
Yes, we can check s->count <= UINT16_MAX before 369. It will make sure we
never overflow.

>
> Carl Eugen
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