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Subject[PATCH 4.9 041/177] iommu/io-pgtable-arm-v7s: Check for leaf entry before dereferencing it
Date
4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>


[ 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>
---
drivers/iommu/io-pgtable-arm-v7s.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

--- 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_
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 */

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