re: iommu/amd: Implement dm_region call-backs

re: iommu/amd: Implement dm_region call-backs

[Dan Carpenter]

Hello Joerg Roedel,

The patch b61238c4a5e1: "iommu/amd: Implement dm_region call-backs"
from May 28, 2015, leads to the following static checker warning:

	drivers/iommu/amd_iommu.c:3153 amd_iommu_get_dm_regions()
	error: potential null dereference 'region'.  (kzalloc returns null)

drivers/iommu/amd_iommu.c
  3138  static void amd_iommu_get_dm_regions(struct device *dev,
  3139                                       struct list_head *head)
  3140  {
  3141          struct unity_map_entry *entry;
  3142          u16 devid;
  3143  
  3144          devid = get_device_id(dev);
  3145  
  3146          list_for_each_entry(entry, &amd_iommu_unity_map, list) {
  3147                  struct iommu_dm_region *region;
  3148  
  3149                  if (devid < entry->devid_start || devid > entry->devid_end)
  3150                          continue;
  3151  
  3152                  region = kzalloc(sizeof(*region), GFP_KERNEL);

No check here.  We may not care and in that case just ignore this
email.  Or add GFP_NOFAIL to silence the warning if you want.

  3153                  region->start = entry->address_start;
  3154                  region->length = entry->address_end - entry->address_start;
  3155                  if (entry->prot & IOMMU_PROT_IR)
  3156                          region->prot |= IOMMU_READ;
  3157                  if (entry->prot & IOMMU_PROT_IW)
  3158                          region->prot |= IOMMU_WRITE;
  3159  
  3160                  list_add_tail(&region->list, head);
  3161          }
  3162  }

regards,
dan carpenter

Re: iommu/amd: Implement dm_region call-backs

[Joerg Roedel]

On Wed, Jun 10, 2015 at 06:39:20PM +0300, Dan Carpenter wrote:
> Hello Joerg Roedel,
> 
> The patch b61238c4a5e1: "iommu/amd: Implement dm_region call-backs"
> from May 28, 2015, leads to the following static checker warning:
> 
> 	drivers/iommu/amd_iommu.c:3153 amd_iommu_get_dm_regions()
> 	error: potential null dereference 'region'.  (kzalloc returns null)

Thanks for the report, I added a check for the return value and folded
it back into the original patch.

What static checker do you use, btw?


	Joerg

Re: iommu/amd: Implement dm_region call-backs

[Dan Carpenter]

On Thu, Jun 11, 2015 at 09:43:27AM +0200, Joerg Roedel wrote:
> On Wed, Jun 10, 2015 at 06:39:20PM +0300, Dan Carpenter wrote:
> > Hello Joerg Roedel,
> > 
> > The patch b61238c4a5e1: "iommu/amd: Implement dm_region call-backs"
> > from May 28, 2015, leads to the following static checker warning:
> > 
> > 	drivers/iommu/amd_iommu.c:3153 amd_iommu_get_dm_regions()
> > 	error: potential null dereference 'region'.  (kzalloc returns null)
> 
> Thanks for the report, I added a check for the return value and folded
> it back into the original patch.
> 
> What static checker do you use, btw?

I'm using Smatch.

The ERR_PTR stuff requires that you run

	smatch_scripts/build_kernel_data.sh

At the start and that takes a couple hours.

regards,
dan carpenter

Re: iommu/amd: Implement dm_region call-backs

[Joerg Roedel]

On Thu, Jun 11, 2015 at 11:02:51AM +0300, Dan Carpenter wrote:
> On Thu, Jun 11, 2015 at 09:43:27AM +0200, Joerg Roedel wrote:
> > What static checker do you use, btw?
> 
> I'm using Smatch.
> 
> The ERR_PTR stuff requires that you run
> 
> 	smatch_scripts/build_kernel_data.sh
> 
> At the start and that takes a couple hours.

I see, thanks.