linux-kernel - Re: [PATCH Trivial] intel-iommu: check return value of device_to

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Message-ID: <20140109120135.GJ29041@8bytes.org>
Date:	Thu, 9 Jan 2014 13:01:35 +0100
From:	Joerg Roedel <joro@...tes.org>
To:	ethan zhao <ethan.zhao@...cle.com>
Cc:	dwmw2@...radead.org, yinghai@...nel.org, bhelgaas@...gle.com,
	jiang.liu@...ux.intel.com, iommu@...ts.linux-foundation.org,
	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH Trivial] intel-iommu: check return value of
 device_to_iommu() before using it

On Thu, Jan 09, 2014 at 09:58:42AM +0800, ethan zhao wrote:
>  drivers/iommu/intel-iommu.c |    2 ++
>  1 files changed, 2 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
> index 40203ad..5b4531a 100644
> --- a/drivers/iommu/intel-iommu.c
> +++ b/drivers/iommu/intel-iommu.c
> @@ -1105,6 +1105,8 @@ static struct device_domain_info
> *iommu_support_dev_iotlb(
>      struct device_domain_info *info;
>      struct intel_iommu *iommu = device_to_iommu(segment, bus, devfn);
> 
> +    if (!iommu)
> +        return NULL;
>      if (!ecap_dev_iotlb_support(iommu->ecap))
>          return NULL;

This call can not fail, iommu_support_dev_iotlb() is only called from
domain_context_mapping_one() which does the iommu==NULL check on its
own before the call.


	Joerg


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