linux-hardening - Re: [PATCH 1/5] string.h: add array-wrappers for (v)memdup

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Date:   Wed, 30 Aug 2023 16:23:10 +0200
From:   pstanner@...hat.com
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Kees Cook <keescook@...omium.org>,
        Andy Shevchenko <andy@...nel.org>,
        Eric Biederman <ebiederm@...ssion.com>,
        Christian Brauner <brauner@...nel.org>,
        David Disseldorp <ddiss@...e.de>,
        Luis Chamberlain <mcgrof@...nel.org>,
        Siddh Raman Pant <code@...dh.me>,
        Nick Alcock <nick.alcock@...cle.com>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>, Zack Rusin <zackr@...are.com>,
        VMware Graphics Reviewers 
        <linux-graphics-maintainer@...are.com>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        kexec@...ts.infradead.org, linux-hardening@...r.kernel.org,
        David Airlie <airlied@...hat.com>
Subject: Re: [PATCH 1/5] string.h: add array-wrappers for (v)memdup_user()

On Wed, 2023-08-30 at 17:15 +0300, Andy Shevchenko wrote:
> On Wed, Aug 30, 2023 at 4:46 PM Philipp Stanner <pstanner@...hat.com>
> wrote:
> 
> > +       if (unlikely(check_mul_overflow(n, size, &nbytes)))
> > +               return ERR_PTR(-EINVAL);
> 
> > +       if (unlikely(check_mul_overflow(n, size, &nbytes)))
> > +               return ERR_PTR(-EINVAL);
> 
> Btw, why not -EOVERFLOW ?
> 

Good question, actually.
To be honest I wasn't quite sure which code to pick (-E2BIG was also
once I candidate).

-EINVAL was picked because the idea was that a request overflowing a
size_t could surely be expected to contain an invalid parameter,
because no one would ever request an array _that_ large

?