From mboxrd@z Thu Jan 1 00:00:00 1970 From: olekstysh@gmail.com (Oleksandr Tyshchenko) Date: Mon, 27 Feb 2017 14:30:26 +0200 Subject: [PATCH v1 2/2] iommu/io-pgtable-arm-v7s: Check for leaf entry before dereferencing it In-Reply-To: <1488198626-1884-1-git-send-email-olekstysh@gmail.com> References: <1488198626-1884-1-git-send-email-olekstysh@gmail.com> Message-ID: <1488198626-1884-3-git-send-email-olekstysh@gmail.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org From: Oleksandr Tyshchenko 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 CC: Will Deacon CC: Robin Murphy --- drivers/iommu/io-pgtable-arm-v7s.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/iommu/io-pgtable-arm-v7s.c b/drivers/iommu/io-pgtable-arm-v7s.c index 1c049e2..8d6ca28 100644 --- 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 */ -- 2.7.4