From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alex Williamson Subject: Re: [PATCH] vfio, iommu: Fixed interaction of VFIO_IOMMU_MAP_DMA with IOMMU address limits Date: Wed, 28 Aug 2013 09:44:32 -0600 Message-ID: <1377704672.10408.81.camel@ul30vt.home> References: <1377597428-21480-1-git-send-email-jsteckli@os.inf.tu-dresden.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1377597428-21480-1-git-send-email-jsteckli-IG//nw+yl+iQIjdd1DhZXWfrygkm6VTR@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Julian Stecklina Cc: iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, David.Woodhouse-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: iommu@lists.linux-foundation.org On Tue, 2013-08-27 at 11:57 +0200, Julian Stecklina wrote: > The BUG_ON in drivers/iommu/intel-iommu.c:785 can be triggered from userspace via > VFIO by calling the VFIO_IOMMU_MAP_DMA ioctl on a vfio device with any address > beyond the addressing capabilities of the IOMMU. The problem is that the ioctl code > calls iommu_iova_to_phys before it calls iommu_map. iommu_map handles the case that > it gets addresses beyond the addressing capabilities of its IOMMU. > intel_iommu_iova_to_phys does not. > > This patch fixes iommu_iova_to_phys to return NULL for addresses beyond what the > IOMMU can handle. This in turn causes the ioctl call to fail in iommu_map and > (correctly) return EFAULT to the user with a helpful warning message in the kernel > log. > > Signed-off-by: Julian Stecklina Acked-by: Alex Williamson > --- > drivers/iommu/intel-iommu.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c > index eec0d3e..61303db 100644 > --- a/drivers/iommu/intel-iommu.c > +++ b/drivers/iommu/intel-iommu.c > @@ -782,7 +782,11 @@ static struct dma_pte *pfn_to_dma_pte(struct dmar_domain *domain, > int offset; > > BUG_ON(!domain->pgd); > - BUG_ON(addr_width < BITS_PER_LONG && pfn >> addr_width); > + > + if (addr_width < BITS_PER_LONG && pfn >> addr_width) > + /* Address beyond IOMMU's addressing capabilities. */ > + return NULL; > + > parent = domain->pgd; > > while (level > 0) {