Re: [FFmpeg-devel] [PATCH] avutil/imgutils: av_image_check_size2() ensure width and height fit in 32bit

[Michael Niedermayer <michael@niedermayer.cc>]

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On Tue, Jul 09, 2024 at 05:14:37PM +0200, Anton Khirnov wrote:
> Quoting Michael Niedermayer (2024-07-09 15:28:10)
> > On Tue, Jul 09, 2024 at 03:17:58PM +0200, Anton Khirnov wrote:
> > > > ensure width and height fit in 32bit
> > > 
> > > why?
> > 
> > because not everyone wants undefined behavior
> > because not everyone wants security issues
> > because we dont support width and height > 32bit and its easier to check in a central place
> > because the changed codes purpose is to check if the image paramaters are
> >     within what we support, and width of 100 billion is not. You can try
> >     all encoders with 100billion width. Then try to decode.
> >     Iam curious, how many work, how many fail and how they fail
> >     how many invalid bitstreams with no warning, how many undefined behaviors, ...
> > 
> > Simply building FFmpeg on a platform with 64bit ints doesnt update
> > ISO and ITU standards to allow larger values
> 
> Quoting Michael Niedermayer (2020-10-07 16:45:56):
> > At least in code i wrote and write i consider it a bug if it would
> > assume sizeof(int/unsigned) == 4
> 
> Make up your mind.

Where do you see a contradiction ?

2020: assuming sizeof(int/unsigned) == 4 is a bug
2024: we do not support more than 32bit width and height,
      nor is that supported by the majority of codec bitsterams and formats
      -> We thus should in a central place check that instead of generating
      undefined behavior and security issues

What i suggest IS actually fixing a "sizeof(int/unsigned) == 4" bug

If someone wants to make the codebase work with 64bit width and height, this
should not be limited to "int is 64bit" systems that would be a very seriously
broken design and also very illogic.

Also your terse replies feel a bit rude

thx

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

No great genius has ever existed without some touch of madness. -- Aristotle

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