linux-kernel - Re: [PATCH] iommu/vt-d: Fix shift overflow in qi_flush_dev

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Message-ID: <20171213071355.GD7780@xz-mi>
Date:   Wed, 13 Dec 2017 15:13:55 +0800
From:   Peter Xu <peterx@...hat.com>
To:     Alex Williamson <alex.williamson@...hat.com>
Cc:     iommu@...ts.linux-foundation.org, tursulin@...ulin.net,
        dwmw2@...radead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] iommu/vt-d: Fix shift overflow in qi_flush_dev_iotlb

On Tue, Dec 12, 2017 at 03:43:08PM -0700, Alex Williamson wrote:

[...]

> diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c
> index 9a7ffd13c7f0..87888b102057 100644
> --- a/drivers/iommu/dmar.c
> +++ b/drivers/iommu/dmar.c
> @@ -1345,7 +1345,9 @@ void qi_flush_dev_iotlb(struct intel_iommu *iommu, u16 sid, u16 qdep,
>  	struct qi_desc desc;
>  
>  	if (mask) {
> -		BUG_ON(addr & ((1 << (VTD_PAGE_SHIFT + mask)) - 1));
> +		BUG_ON((mask > MAX_AGAW_PFN_WIDTH) ||
> +		       ((mask == MAX_AGAW_PFN_WIDTH) && addr) ||
> +		       (addr & ((1 << (VTD_PAGE_SHIFT + mask)) - 1)));

Could it work if we just use 1ULL instead of 1 here?  Thanks,

-- 
Peter Xu