linux-hardening - Re: [PATCH] docs: deprecated.rst: Clarify open-coded arithmetic with literals

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Date:   Sun, 29 Aug 2021 16:32:00 +0200
From:   Len Baker <len.baker@....com>
To:     Joe Perches <joe@...ches.com>
Cc:     Len Baker <len.baker@....com>, Jonathan Corbet <corbet@....net>,
        Kees Cook <keescook@...omium.org>,
        "Gustavo A. R. Silva" <gustavoars@...nel.org>,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-hardening@...r.kernel.org
Subject: Re: [PATCH] docs: deprecated.rst: Clarify open-coded arithmetic with
 literals

Hi,

On Fri, Aug 27, 2021 at 12:06:18PM -0700, Joe Perches wrote:
> On Fri, 2021-08-27 at 19:12 +0200, Len Baker wrote:
> > Although using literals for size calculation in allocator arguments may
> > be harmless due to compiler warnings in case of overflows, it is better
> > to refactor the code to avoid the use of open-coded math idiom.
> >
> > So, clarify the preferred way in these cases.
> []
> > diff --git a/Documentation/process/deprecated.rst b/Documentation/process/deprecated.rst
> []
> > @@ -60,7 +60,8 @@ smaller allocation being made than the caller was expecting. Using those
> >  allocations could lead to linear overflows of heap memory and other
> >  misbehaviors. (One exception to this is literal values where the compiler
> >  can warn if they might overflow. Though using literals for arguments as
> > -suggested below is also harmless.)
> > +suggested below is also harmless. So, the preferred way in these cases is
> > +to refactor the code to keep the open-coded math idiom out.)
>
> wordsmithing trivia:
>
> 'keep <foo> out' is difficult to parse as 'keep' is generally a positive
> word but its meaning is later reversed with out.
>
> 'avoid <foo>' maybe be better phrasing.
>
Understood. I will do this change and I will send a new version.
Thanks for the review.

Regards,
Len