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

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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>
This commit is contained in:
Oleksandr Tyshchenko 2017-02-27 14:30:25 +02:00 committed by Will Deacon
parent c1ae3cfa0e
commit ed46e66cc1
1 changed files with 5 additions and 1 deletions
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6
drivers/iommu/io-pgtable-arm.c
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@ -335,8 +335,12 @@ static int __arm_lpae_map(struct arm_lpae_io_pgtable *data, unsigned long iova,
if (cfg->quirks & IO_PGTABLE_QUIRK_ARM_NS)
pte |= ARM_LPAE_PTE_NSTABLE;
__arm_lpae_set_pte(ptep, pte, cfg);
} else {
} else if (!iopte_leaf(pte, lvl)) {
cptep = iopte_deref(pte, data);
} else {
/* We require an unmap first */
WARN_ON(!selftest_running);
return -EEXIST;
}
/* Rinse, repeat */