Subject: Re: [PATCH 19/32] afs: Use mem_to_flex_dup() with struct afs_acl

From: Kees Cook <[email-masked]>
Date: Fri, 13 May 2022 08:44:33 -0700

On Thu, May 12, 2022 at 10:41:05PM +0100, David Howells wrote:
> 
> Kees Cook <[email-masked]> wrote:
> 
> >  struct afs_acl {
> > -	u32	size;
> > -	u8	data[];
> > +	DECLARE_FLEX_ARRAY_ELEMENTS_COUNT(u32, size);
> > +	DECLARE_FLEX_ARRAY_ELEMENTS(u8, data);
> >  };
> 
> Oof...  That's really quite unpleasant syntax.  Is it not possible to have
> mem_to_flex_dup() and friends work without that?  You are telling them the
> fields they have to fill in.

Other threads discussed this too. I'm hoping to have something more
flexible (pardon the pun) in v2.

> [...]
> or:
> 
> 	ret = mem_to_flex_dup(&acl, buffer, size, GFP_KERNEL);
> 	if (ret < 0)
> 
> (or use != 0 rather than < 0)

Sure, I can make the tests more explicit. The kerndoc, etc all shows it's
using < 0 for errors.

-- 
Kees Cook