Re: [PATCH] iommu/amd: Check if domain is NULL before dereference it

[Baoquan He <bhe-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

On 08/24/17 at 03:53pm, Dan Carpenter wrote:
> On Thu, Aug 24, 2017 at 08:47:33PM +0800, Baoquan He wrote:
> > On 08/24/17 at 03:32pm, Dan Carpenter wrote:
> > > Take a look at this code for example.  But all the places which call
> > > get_domain() are the same:
> > > 
> > > drivers/iommu/amd_iommu.c
> > >   2648          page = virt_to_page(virt_addr);
> > >   2649          size = PAGE_ALIGN(size);
> > >   2650  
> > >   2651          domain = get_domain(dev);
> > >                          ^^^^^^^^^^^^^^
> > > imagined get_domain() returns NULL.
> > > 
> > >   2652          if (IS_ERR(domain))
> > >   2653                  goto free_mem;
> > >   2654  
> > >   2655          dma_dom = to_dma_ops_domain(domain);
> > >                           ^^^^^^^^^^^^^^^^^^^^^^^^^
> > > This will Oops.
> > 
> > I see, it's a problem. Thanks for telling!
> > 
> > How about below change? But I am not very sure which errno should be
> > picked, seems the latter one, EBUSY is better since it has passed the
> > check_device() checking.
> 
> Looks good to me.  You know better than I do which errno is best, so
> I'll leave that to you.

OK, thanks! Then let me post v2 with it.