Messages in this thread | | | Subject | Re: [PATCH] vfio, iommu: Fixed interaction of VFIO_IOMMU_MAP_DMA with IOMMU address limits | From | Alex Williamson <> | Date | Wed, 28 Aug 2013 09:44:32 -0600 |
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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 <jsteckli@os.inf.tu-dresden.de>
Acked-by: Alex Williamson <alex.williamson@redhat.com>
> --- > 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) {
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