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 <jstec...@os.inf.tu-dresden.de>
Acked-by: Alex Williamson <alex.william...@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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