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 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
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