linux-kernel - Re: [PATCH] overflow.h: Add flex_array

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Message-ID: <20200609004756.GH10051@embeddedor>
Date:   Mon, 8 Jun 2020 19:47:56 -0500
From:   "Gustavo A. R. Silva" <gustavoars@...nel.org>
To:     Joe Perches <joe@...ches.com>
Cc:     Kees Cook <keescook@...omium.org>, linux-kernel@...r.kernel.org,
        "Gustavo A. R. Silva" <gustavo@...eddedor.com>
Subject: Re: [PATCH] overflow.h: Add flex_array_size() helper

On Mon, Jun 08, 2020 at 03:34:52PM -0700, Joe Perches wrote:
> On Mon, 2020-06-08 at 17:17 -0500, Gustavo A. R. Silva wrote:
> > Add flex_array_size() helper for the calculation of the size, in bytes,
> > of a flexible array member contained within an enclosing structure.
> > 
> > Example of usage:
> > foo
> > struct something {
> > 	size_t count;
> > 	struct foo items[];
> > };
> > 
> > struct something *instance;
> []
> > diff --git a/include/linux/overflow.h b/include/linux/overflow.h
> []
> > +/**
> > + * flex_array_size() - Calculate size of a flexible array member within
> > + * an enclosing structure.
> 
> These comment descriptions do not match
> 
> > + * Calculates size of memory needed for flexible array @member of @count
> > + * elements within structure @p.
> 
> The first comment shows the size of an array member.
> The second shows the size of an array member * count
> 
> Also the struct_size and flex_array_size definitions
> are using two different forms:
> 
> 		sizeof(*(p)->member) + __must_be_array((p)->member),\
> and
> 		sizeof((p)->member[0]) + __must_be_array((p)->member))
> 

Good catch.

Thanks
--
Gustavo