[bug report] iommu/vt-d: Allocate/register iopf queue for sva devices

[bug report] iommu/vt-d: Allocate/register iopf queue for sva devices

[Dan Carpenter]

Hello Lu Baolu,

This is a semi-automatic email about new static checker warnings.

The patch 4c82b88696ac: "iommu/vt-d: Allocate/register iopf queue for 
sva devices" from Jun 10, 2021, leads to the following Smatch 
complaint:

    drivers/iommu/intel/iommu.c:5335 intel_iommu_enable_sva()
    warn: variable dereferenced before check 'info' (see line 5332)

drivers/iommu/intel/iommu.c
  5331		struct device_domain_info *info = get_domain_info(dev);
  5332		struct intel_iommu *iommu = info->iommu;
                                            ^^^^^^^^^^^
Dereferenced

  5333		int ret;
  5334	
  5335		if (!info || !iommu || dmar_disabled)
                    ^^^^^
Checked too late.  <dramatic prairie dog.gif>


  5336			return -EINVAL;
  5337	

regards,
dan carpenter
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Re: [bug report] iommu/vt-d: Allocate/register iopf queue for sva devices

[Lu Baolu]

Thanks for letting me know this. We already have a fix in linux-next.

commit 90141a0fb72340937ed9ec05301cc548901d8eec
Author: Colin Ian King <colin.king@canonical.com>
Date:   Fri Jun 11 14:50:24 2021 +0100

     iommu/vt-d: Fix dereference of pointer info before it is null checked

     The assignment of iommu from info->iommu occurs before info is null 
checked
     hence leading to a potential null pointer dereference issue. Fix 
this by
     assigning iommu and checking if iommu is null after null checking info.

     Fixes: 4c82b88696ac ("iommu/vt-d: Allocate/register iopf queue for 
sva devices")
     Signed-off-by: Colin Ian King <colin.king@canonical.com>
     Addresses-Coverity: ("Dereference before null check")
     Link: 
https://lore.kernel.org/r/20210611135024.32781-1-colin.king@canonical.com
     Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>

Best regards,
baolu

On 2021/6/18 14:55, Dan Carpenter wrote:
> Hello Lu Baolu,
> 
> This is a semi-automatic email about new static checker warnings.
> 
> The patch 4c82b88696ac: "iommu/vt-d: Allocate/register iopf queue for
> sva devices" from Jun 10, 2021, leads to the following Smatch
> complaint:
> 
>      drivers/iommu/intel/iommu.c:5335 intel_iommu_enable_sva()
>      warn: variable dereferenced before check 'info' (see line 5332)
> 
> drivers/iommu/intel/iommu.c
>    5331		struct device_domain_info *info = get_domain_info(dev);
>    5332		struct intel_iommu *iommu = info->iommu;
>                                              ^^^^^^^^^^^
> Dereferenced
> 
>    5333		int ret;
>    5334	
>    5335		if (!info || !iommu || dmar_disabled)
>                      ^^^^^
> Checked too late.  <dramatic prairie dog.gif>
> 
> 
>    5336			return -EINVAL;
>    5337	
> 
> regards,
> dan carpenter
> 
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