| From | Luis Henriques <> | Subject | [PATCH 3.5 052/103] iommu/vt-d: Fixed interaction of VFIO_IOMMU_MAP_DMA with IOMMU address limits | Date | Tue, 17 Dec 2013 18:12:41 +0000 |
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3.5.7.28 -stable review patch. If anyone has any objections, please let me know.
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From: Julian Stecklina <jsteckli@os.inf.tu-dresden.de>
commit f9423606ade08653dd8a43334f0a7fb45504c5cc upstream.
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> Signed-off-by: Joerg Roedel <joro@8bytes.org> Cc: Josh Boyer <jwboyer@fedoraproject.org> Signed-off-by: Luis Henriques <luis.henriques@canonical.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 e560f54..f3535d9 100644 --- a/drivers/iommu/intel-iommu.c +++ b/drivers/iommu/intel-iommu.c @@ -779,7 +779,11 @@ 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) { -- 1.8.3.2
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