From mboxrd@z Thu Jan 1 00:00:00 1970 From: Julian Stecklina Subject: [PATCH] vfio, iommu: Fixed interaction of VFIO_IOMMU_MAP_DMA with IOMMU address limits Date: Wed, 9 Oct 2013 10:03:52 +0200 Message-ID: <1381305832-2900-1-git-send-email-jsteckli@os.inf.tu-dresden.de> References: <1377704672.10408.81.camel@ul30vt.home> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1377704672.10408.81.camel-85EaTFmN5p//9pzu0YdTqQ@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: Joerg Roedel , David Woodhouse Cc: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, Julian Stecklina List-Id: iommu@lists.linux-foundation.org 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 15e9b57..40203ad 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) { -- 1.8.3.1