[PATCH] iommu/io-pgtable: Sanitise map/unmap addresses

[Robin Murphy]

It may be an egregious error to attempt to use addresses outside the
range of the pagetable format, but that still doesn't mean we should
merrily wreak havoc by silently mapping/unmapping whatever truncated
portions of them might happen to correspond to real addresses.

Add some up-front checks to sanitise our inputs so that buggy callers
don't invite potential memory corruption.

Signed-off-by: Robin Murphy <robin.murphy at arm.com>
---
 drivers/iommu/io-pgtable-arm-v7s.c | 6 ++++++
 drivers/iommu/io-pgtable-arm.c     | 7 +++++++
 2 files changed, 13 insertions(+)

diff --git a/drivers/iommu/io-pgtable-arm-v7s.c b/drivers/iommu/io-pgtable-arm-v7s.c
index 7753b33d041d..e0bfe8ba4c9d 100644
--- a/drivers/iommu/io-pgtable-arm-v7s.c
+++ b/drivers/iommu/io-pgtable-arm-v7s.c
@@ -475,6 +475,9 @@ static int arm_v7s_map(struct io_pgtable_ops *ops, unsigned long iova,
 	if (!(prot & (IOMMU_READ | IOMMU_WRITE)))
 		return 0;
 
+	if (WARN_ON(upper_32_bits(iova) || upper_32_bits(paddr)))
+		return -ERANGE;
+
 	ret = __arm_v7s_map(data, iova, paddr, size, prot, 1, data->pgd);
 	/*
 	 * Synchronise all PTE updates for the new mapping before there's
@@ -655,6 +658,9 @@ static int arm_v7s_unmap(struct io_pgtable_ops *ops, unsigned long iova,
 	struct arm_v7s_io_pgtable *data = io_pgtable_ops_to_data(ops);
 	size_t unmapped;
 
+	if (WARN_ON(upper_32_bits(iova)))
+		return 0;
+
 	unmapped = __arm_v7s_unmap(data, iova, size, 1, data->pgd);
 	if (unmapped)
 		io_pgtable_tlb_sync(&data->iop);
diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
index f73120f2cfbc..ebf9152c2422 100644
--- a/drivers/iommu/io-pgtable-arm.c
+++ b/drivers/iommu/io-pgtable-arm.c
@@ -448,6 +448,10 @@ static int arm_lpae_map(struct io_pgtable_ops *ops, unsigned long iova,
 	if (!(iommu_prot & (IOMMU_READ | IOMMU_WRITE)))
 		return 0;
 
+	if (WARN_ON(iova >= (1ULL << data->iop.cfg.ias) ||
+		    paddr >= (1ULL << data->iop.cfg.oas)))
+		return -ERANGE;
+
 	prot = arm_lpae_prot_to_pte(data, iommu_prot);
 	ret = __arm_lpae_map(data, iova, paddr, size, prot, lvl, ptep);
 	/*
@@ -606,6 +610,9 @@ static int arm_lpae_unmap(struct io_pgtable_ops *ops, unsigned long iova,
 	arm_lpae_iopte *ptep = data->pgd;
 	int lvl = ARM_LPAE_START_LVL(data);
 
+	if (WARN_ON(iova >= (1ULL << data->iop.cfg.ias)))
+		return 0;
+
 	unmapped = __arm_lpae_unmap(data, iova, size, lvl, ptep);
 	if (unmapped)
 		io_pgtable_tlb_sync(&data->iop);
-- 
2.12.2.dirty