linux-kernel - [PATCH 4.2.y-ckt 035/268] iommu/io-pgtable-arm: Ensure we free the final level on teardown

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Message-Id: <1453926929-17663-36-git-send-email-kamal@canonical.com>
Date:	Wed, 27 Jan 2016 12:31:36 -0800
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Will Deacon <will.deacon@....com>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 4.2.y-ckt 035/268] iommu/io-pgtable-arm: Ensure we free the final level on teardown

4.2.8-ckt3 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Will Deacon <will.deacon@....com>

commit 12c2ab09571e8aae3a87da2a4a452632a5fac1e5 upstream.

When tearing down page tables, we return early for the final level
since we know that we won't have any table pointers to follow.
Unfortunately, this also means that we forget to free the final level,
so we end up leaking memory.

Fix the issue by always freeing the current level, but just don't bother
to iterate over the ptes if we're at the final level.

Reported-by: Zhang Bo <zhangbo_a@...omi.com>
Signed-off-by: Will Deacon <will.deacon@....com>
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
 drivers/iommu/io-pgtable-arm.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
index e29d5d7..937832c 100644
--- a/drivers/iommu/io-pgtable-arm.c
+++ b/drivers/iommu/io-pgtable-arm.c
@@ -341,17 +341,18 @@ static void __arm_lpae_free_pgtable(struct arm_lpae_io_pgtable *data, int lvl,
 	arm_lpae_iopte *start, *end;
 	unsigned long table_size;
 
-	/* Only leaf entries at the last level */
-	if (lvl == ARM_LPAE_MAX_LEVELS - 1)
-		return;
-
 	if (lvl == ARM_LPAE_START_LVL(data))
 		table_size = data->pgd_size;
 	else
 		table_size = 1UL << data->pg_shift;
 
 	start = ptep;
-	end = (void *)ptep + table_size;
+
+	/* Only leaf entries at the last level */
+	if (lvl == ARM_LPAE_MAX_LEVELS - 1)
+		end = ptep;
+	else
+		end = (void *)ptep + table_size;
 
 	while (ptep != end) {
 		arm_lpae_iopte pte = *ptep++;
-- 
1.9.1