Patch "iommu/io-pgtable-arm: Check for leaf entry before dereferencing it" has been added to the 4.9-stable tree

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 4.9-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-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Oleksandr Tyshchenko <[email protected]>
Date: Mon, 27 Feb 2017 14:30:25 +0200
Subject: iommu/io-pgtable-arm: Check for leaf entry before dereferencing it

From: Oleksandr Tyshchenko <[email protected]>

[ 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.

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

@@ -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 [email protected] are

queue-4.9/iommu-io-pgtable-arm-check-for-leaf-entry-before-dereferencing-it.patch