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

[ Upstream commit a03849e7210277fa212779b7cd9c30e1ab6194b2 ]

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>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/iommu/io-pgtable-arm-v7s.c b/drivers/iommu/io-pgtable-arm-v7s.c
index f50e51c..d68a552 100644 (file)
--- a/drivers/iommu/io-pgtable-arm-v7s.c
+++ b/drivers/iommu/io-pgtable-arm-v7s.c
@@ -418,8 +418,12 @@ 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 */