From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754522Ab3H1Pok (ORCPT ); Wed, 28 Aug 2013 11:44:40 -0400 Received: from mx1.redhat.com ([209.132.183.28]:36375 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754026Ab3H1Poj (ORCPT ); Wed, 28 Aug 2013 11:44:39 -0400 Message-ID: <1377704672.10408.81.camel@ul30vt.home> Subject: Re: [PATCH] vfio, iommu: Fixed interaction of VFIO_IOMMU_MAP_DMA with IOMMU address limits From: Alex Williamson To: Julian Stecklina Cc: David.Woodhouse@intel.com, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org Date: Wed, 28 Aug 2013 09:44:32 -0600 In-Reply-To: <1377597428-21480-1-git-send-email-jsteckli@os.inf.tu-dresden.de> References: <1377597428-21480-1-git-send-email-jsteckli@os.inf.tu-dresden.de> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.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) {