iommu/io-pgtable-arm-v7s: Check for leaf entry before dereferencing it

Do a check for already installed leaf entry at the current level before
dereferencing it in order to avoid walking the page table down with
wrong pointer to the next level.

Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
CC: Will Deacon <will.deacon@arm.com>
CC: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

diff --git a/drivers/iommu/io-pgtable-arm-v7s.c b/drivers/iommu/io-pgtable-arm-v7s.c
index 1c049e2e12bf0ddacbc0e8ff9cbb09751996a549..8d6ca28c3e1f14a6c364aae89640ee6535f8f0d6 100644 (file)
--- a/drivers/iommu/io-pgtable-arm-v7s.c
+++ b/drivers/iommu/io-pgtable-arm-v7s.c
@@ -422,8 +422,12 @@ static int __arm_v7s_map(struct arm_v7s_io_pgtable *data, unsigned long iova,
                        pte |= ARM_V7S_ATTR_NS_TABLE;
 
                __arm_v7s_set_pte(ptep, pte, 1, cfg);
-       } else {
+       } else if (ARM_V7S_PTE_IS_TABLE(pte, lvl)) {
                cptep = iopte_deref(pte, lvl);
+       } else {
+               /* We require an unmap first */
+               WARN_ON(!selftest_running);
+               return -EEXIST;
        }
 
        /* Rinse, repeat */