Hi Dan,
On 08/24/17 at 02:04pm, Dan Carpenter wrote:
> Hello Baoquan He,
>
> This is a semi-automatic email about new static checker warnings.
>
> The patch df3f7a6e8e85: "iommu/amd: Use is_attach_deferred call-back"
> from Aug 9, 2017, leads to the following Smatch complaint:
>
> drivers/iommu/amd_iommu.c:2265 get_domain()
> error: we previously assumed 'domain' could be null (see line 2259)
>
> drivers/iommu/amd_iommu.c
> 2258 domain = get_dev_data(dev)->domain;
> 2259 if (domain == NULL && get_dev_data(dev)->defer_attach) {
> ^^^^^^^^^^^^^^
> The patch adds a new check for NULL.
>
> 2260 get_dev_data(dev)->defer_attach = false;
> 2261 io_domain = iommu_get_domain_for_dev(dev);
> 2262 domain = to_pdomain(io_domain);
> 2263 attach_device(dev, domain);
> 2264 }
> 2265 if (!dma_ops_domain(domain))
Thanks for pointing it out, it's truly a code bug. We should check if
'domain' is NULL when pass it to dma_ops_domain() to dereference.
I would like to fix it with below code change, and will post a patch
soon.
- if (!dma_ops_domain(domain))
+ if (domain && !dma_ops_domain(domain))
return ERR_PTR(-EBUSY);
Thanks
Baoquan
> ^^^^^^
> Existing unchecked dereference inside the function.
>
> 2266 return ERR_PTR(-EBUSY);
> 2267
>
> regards,
> dan carpenter
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