Patch "iommu/io-pgtable-arm: Check for leaf entry before dereferencing it" has been added to the 4.4-stable tree

Patch "iommu/io-pgtable-arm: Check for leaf entry before dereferencing it" has been added to the 4.4-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

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

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     iommu-io-pgtable-arm-check-for-leaf-entry-before-dereferencing-it.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Thu Oct  5 10:49:14 CEST 2017
From: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
Date: Mon, 27 Feb 2017 14:30:25 +0200
Subject: iommu/io-pgtable-arm: Check for leaf entry before dereferencing it

From: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.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@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.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

--- 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_lpa
 		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 */


Patches currently in stable-queue which might be from oleksandr_tyshchenko@epam.com are

queue-4.4/iommu-io-pgtable-arm-check-for-leaf-entry-before-dereferencing-it.patch