linux-kernel - Re: [PATCH] usercopy: add testcases to check zeroing on failure of usercopy

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Date:   Mon, 13 Feb 2017 10:21:13 -0800
From:   Kees Cook <keescook@...omium.org>
To:     Hoeun Ryu <hoeun.ryu@...il.com>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        "kernel-hardening@...ts.openwall.com" 
        <kernel-hardening@...ts.openwall.com>
Subject: Re: [PATCH] usercopy: add testcases to check zeroing on failure of usercopy

On Sat, Feb 11, 2017 at 10:13 PM, Hoeun Ryu <hoeun.ryu@...il.com> wrote:
> In the hardend usercopy, the destination buffer will be zeroed if
> copy_from_user/get_user fails. This patch adds testcases for it.
> The destination buffer is set with non-zero value before illegal
> copy_from_user/get_user is executed and the buffer is compared to
> zero after usercopy is done.
>
> Signed-off-by: Hoeun Ryu <hoeun.ryu@...il.com>

This looks great!

I'll adjust the commit slightly (the zeroing always happens,
regardless of hardened usercopy) and add it to my usercopy tree.

Thanks!

-Kees

-- 
Kees Cook
Pixel Security