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Date: Mon, 18 Sep 2017 00:40:34 +0000 From: "Levin, Alexander (Sasha Levin)" <alexander.levin@...izon.com> To: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "stable@...r.kernel.org" <stable@...r.kernel.org> Cc: Oleksandr Tyshchenko <oleksandr_tyshchenko@...m.com>, Will Deacon <will.deacon@....com>, Robin Murphy <robin.murphy@....com>, "Levin, Alexander (Sasha Levin)" <alexander.levin@...izon.com> Subject: [PATCH for 4.9 28/39] iommu/io-pgtable-arm: Check for leaf entry before dereferencing it From: Oleksandr Tyshchenko <oleksandr_tyshchenko@...m.com> [ Upstream commit ed46e66cc1b3d684042f92dfa2ab15ee917b4cac ] 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@...m.com> CC: Will Deacon <will.deacon@....com> CC: Robin Murphy <robin.murphy@....com> Signed-off-by: Will Deacon <will.deacon@....com> Signed-off-by: Sasha Levin <alexander.levin@...izon.com> --- drivers/iommu/io-pgtable-arm.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c index f5c90e1366ce..7c9d632f1d09 100644 --- a/drivers/iommu/io-pgtable-arm.c +++ b/drivers/iommu/io-pgtable-arm.c @@ -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 */ -- 2.11.0
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