linux-kernel - Re: [PATCH 2/2] iommu/vt-d: Check if domain->pgd was allocated

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Date:   Fri, 19 Jul 2019 17:15:21 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     Dmitry Safonov <dima@...sta.com>, linux-kernel@...r.kernel.org
Cc:     baolu.lu@...ux.intel.com, Dmitry Safonov <0x7f454c46@...il.com>,
        David Woodhouse <dwmw2@...radead.org>,
        Joerg Roedel <joro@...tes.org>,
        iommu@...ts.linux-foundation.org
Subject: Re: [PATCH 2/2] iommu/vt-d: Check if domain->pgd was allocated

Hi,

On 7/17/19 5:38 AM, Dmitry Safonov wrote:
> There is a couple of places where on domain_init() failure domain_exit()
> is called. While currently domain_init() can fail only if
> alloc_pgtable_page() has failed.
> 
> Make domain_exit() check if domain->pgd present, before calling
> domain_unmap(), as it theoretically should crash on clearing pte entries
> in dma_pte_clear_level().
> 
> Cc: David Woodhouse <dwmw2@...radead.org>
> Cc: Joerg Roedel <joro@...tes.org>
> Cc: Lu Baolu <baolu.lu@...ux.intel.com>

This looks good to me. Thank you!

Reviewed-by: Lu Baolu <baolu.lu@...ux.intel.com>

Best regards,
Baolu

> Cc: iommu@...ts.linux-foundation.org
> Signed-off-by: Dmitry Safonov <dima@...sta.com>
> ---
>   drivers/iommu/intel-iommu.c | 8 +++++---
>   1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
> index 6d1510284d21..698cc40355ef 100644
> --- a/drivers/iommu/intel-iommu.c
> +++ b/drivers/iommu/intel-iommu.c
> @@ -1835,7 +1835,6 @@ static inline int guestwidth_to_adjustwidth(int gaw)
>   
>   static void domain_exit(struct dmar_domain *domain)
>   {
> -	struct page *freelist;
>   
>   	/* Remove associated devices and clear attached or cached domains */
>   	domain_remove_dev_info(domain);
> @@ -1843,9 +1842,12 @@ static void domain_exit(struct dmar_domain *domain)
>   	/* destroy iovas */
>   	put_iova_domain(&domain->iovad);
>   
> -	freelist = domain_unmap(domain, 0, DOMAIN_MAX_PFN(domain->gaw));
> +	if (domain->pgd) {
> +		struct page *freelist;
>   
> -	dma_free_pagelist(freelist);
> +		freelist = domain_unmap(domain, 0, DOMAIN_MAX_PFN(domain->gaw));
> +		dma_free_pagelist(freelist);
> +	}
>   
>   	free_domain_mem(domain);
>   }
>