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Message-ID: <9ff9dd41ff99560dcb3eb78f5835da67293f860c.camel@surriel.com>
Subject: Re: [PATCH v2] x86/nmi: Fix some races in NMI uaccess
From:   Rik van Riel <riel@surriel.com>
To:     Andy Lutomirski <luto@kernel.org>, x86@kernel.org,
        Nadav Amit <nadav.amit@gmail.com>
Cc:     Borislav Petkov <bp@alien8.de>, Jann Horn <jannh@google.com>,
        LKML <linux-kernel@vger.kernel.org>, stable@vger.kernel.org,
        Peter Zijlstra <peterz@infradead.org>
Date:   Wed, 29 Aug 2018 12:06:54 -0400
In-Reply-To: <dd956eba16646fd0b15c3c0741269dfd84452dac.1535557289.git.luto@kernel.org>
References: <dd956eba16646fd0b15c3c0741269dfd84452dac.1535557289.git.luto@kernel.org>
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On Wed, 2018-08-29 at 08:47 -0700, Andy Lutomirski wrote:
> In NMI context, we might be in the middle of context switching or in
> the middle of switch_mm_irqs_off().  In either case, CR3 might not
> match current->mm, which could cause copy_from_user_nmi() and
> friends to read the wrong memory.
>=20
> Fix it by adding a new nmi_uaccess_okay() helper and checking it in
> copy_from_user_nmi() and in __copy_from_user_nmi()'s callers.
>=20
> Cc: stable@vger.kernel.org
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Nadav Amit <nadav.amit@gmail.com>
> Signed-off-by: Andy Lutomirski <luto@kernel.org>

Reviewed-by: Rik van Riel <riel@surriel.com>

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