linux-kernel - Re: [PATCH v3 1/2] sysctl: handle overflow in proc_get

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Message-ID: <CAGXu5jJTaOyzPUYMCi9_vbxCUhLz09C-LEQL9dmM+pt_xfxcQw@mail.gmail.com>
Date:   Tue, 16 Oct 2018 19:19:35 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Christian Brauner <christian@...uner.io>
Cc:     "Eric W . Biederman" <ebiederm@...ssion.com>,
        LKML <linux-kernel@...r.kernel.org>,
        "Luis R. Rodriguez" <mcgrof@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Joe Lawrence <joe.lawrence@...hat.com>,
        Waiman Long <longman@...hat.com>,
        Dominik Brodowski <linux@...inikbrodowski.net>,
        Al Viro <viro@...iv.linux.org.uk>,
        Alexey Dobriyan <adobriyan@...il.com>,
        Linux API <linux-api@...r.kernel.org>
Subject: Re: [PATCH v3 1/2] sysctl: handle overflow in proc_get_long

On Tue, Oct 16, 2018 at 5:24 PM, Christian Brauner <christian@...uner.io> wrote:
> Right, but if you write a value that exceeds the buffer of 22 chars that is used
> to parse you already get EINVAL back on current kernels.
> So it didn't feel like returning EOVERFLOW or ERANGE might make sense.
> I saw a change in 4.10 or 4.11 as well that used EINVAL on UINT_MAX overflow
> or something. EINVAL might be enough information for userspace here ?/.

I'd agree: I think there is more precedent for EINVAL.

-Kees

-- 
Kees Cook
Pixel Security