linux-kernel - Re: [PATCH 1/1] iommu: Don't use lazy flush for untrusted device

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Message-ID: <20210325145723.GB15172@willie-the-truck>
Date:   Thu, 25 Mar 2021 14:57:23 +0000
From:   Will Deacon <will@...nel.org>
To:     Lu Baolu <baolu.lu@...ux.intel.com>
Cc:     Joerg Roedel <joro@...tes.org>, iommu@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] iommu: Don't use lazy flush for untrusted device

On Thu, Feb 25, 2021 at 02:14:54PM +0800, Lu Baolu wrote:
> The lazy IOTLB flushing setup leaves a time window, in which the device
> can still access some system memory, which has already been unmapped by
> the device driver. It's not suitable for untrusted devices. A malicious
> device might use this to attack the system by obtaining data that it
> shouldn't obtain.
> 
> Fixes: c588072bba6b5 ("iommu/vt-d: Convert intel iommu driver to the iommu ops")
> Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
> ---
>  drivers/iommu/dma-iommu.c | 15 ++++++++-------
>  1 file changed, 8 insertions(+), 7 deletions(-)

Acked-by: Will Deacon <will@...nel.org>

Will