linux-kernel - Re: [kernel-hardening] Re: [PATCH] checkpatch: Add ability to find bad uses of vsprintf %p<foo> extensions

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Message-ID: <CAGXu5j+dZvZPnmWMVsgSL706m_mR+h7FGd1HS4TgKmXhYhA4Hw@mail.gmail.com>
Date:   Tue, 28 Feb 2017 16:11:46 -0800
From:   Kees Cook <keescook@...omium.org>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Joe Perches <joe@...ches.com>, Andy Whitcroft <apw@...onical.com>,
        "Roberts, William C" <william.c.roberts@...el.com>,
        "kernel-hardening@...ts.openwall.com" 
        <kernel-hardening@...ts.openwall.com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [kernel-hardening] Re: [PATCH] checkpatch: Add ability to find
 bad uses of vsprintf %p<foo> extensions

On Tue, Feb 28, 2017 at 4:06 PM, Andrew Morton
<akpm@...ux-foundation.org> wrote:
> On Mon, 27 Feb 2017 12:54:55 -0800 Joe Perches <joe@...ches.com> wrote:
>
>> %pK was at least once misused at %pk in an out-of-tree module.
>> This lead to some security concerns.  Add the ability to track
>> single and multiple line statements for misuses of %p<foo>.
>
> Should we also do this?

Ah yes, good idea. Maybe "...when adding/removing new conversion..." ?

-Kees

>
> --- a/lib/vsprintf.c~checkpatch-add-ability-to-find-bad-uses-of-vsprintf-%pfoo-extensions-fix
> +++ a/lib/vsprintf.c
> @@ -1477,6 +1477,9 @@ int kptr_restrict __read_mostly;
>   * by an extra set of alphanumeric characters that are extended format
>   * specifiers.
>   *
> + * Please update scripts/checkpatch.pl when adding new conversion characters.
> + * (search for "check for vsprintf extension").
> + *
>   * Right now we handle:
>   *
>   * - 'F' For symbolic function descriptor pointers with offset
> _
>



-- 
Kees Cook
Pixel Security