linux-hardening - Re: [PATCH] string: Add additional __realloc

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Date: Thu, 2 May 2024 07:54:10 -0700
From: Kees Cook <keescook@...omium.org>
To: Andy Shevchenko <andy.shevchenko@...il.com>
Cc: Andy Shevchenko <andy@...nel.org>, linux-hardening@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] string: Add additional __realloc_size() annotations for
 "dup" helpers

On Thu, May 02, 2024 at 12:45:33PM +0300, Andy Shevchenko wrote:
> On Thu, May 2, 2024 at 2:32 AM Kees Cook <keescook@...omium.org> wrote:
> >
> > Several other "dup"-style interfaces could use the __realloc_size()
> > attribute. (As a reminder to myself and others: "realloc" is used here
> > instead of "alloc" because the "alloc_size" attribute implies that the
> > memory contents are uninitialized. Since we're copying contents into the
> > resulting allocation, it must use "realloc_size" to avoid confusing the
> > compiler's optimization passes.)
> >
> > Add KUnit test coverage where possible. (KUnit still does not have the
> > ability to manipulate userspace memory.)
> 
> Makes sense to me,
> Reviewed-by: Andy Shevchenko <andy@...nel.org>
> 
> ...
> 
> > +               checker(len, kmemdup_array(test_phrases[idx], len, 1,   \
> > +                                          gfp), kfree(p));             \
> 
> Despite being longer, I would put gfp on the previous line for the
> sake of logical split (and additionally to be consistent with the
> below).
> 
> > +               checker(len, kmemdup(test_phrases[idx], len, gfp),      \
> > +                       kfree(p));                                      \

Oh good! This bothered me to no end too. I will adjust it. :) Thanks!

-Kees

-- 
Kees Cook