[PATCH 5.4 043/149] iommu/arm-smmu: Fix arm_smmu_device refcount leak in address translation

[Greg Kroah-Hartman]

From: Xiyu Yang <xiyuyang19@xxxxxxxxxxxx>

[ Upstream commit 7c8f176d6a3fa18aa0f8875da6f7c672ed2a8554 ]

The reference counting issue happens in several exception handling paths
of arm_smmu_iova_to_phys_hard(). When those error scenarios occur, the
function forgets to decrease the refcount of "smmu" increased by
arm_smmu_rpm_get(), causing a refcount leak.

Fix this issue by jumping to "out" label when those error scenarios
occur.

Signed-off-by: Xiyu Yang <xiyuyang19@xxxxxxxxxxxx>
Signed-off-by: Xin Tan <tanxin.ctf@xxxxxxxxx>
Reviewed-by: Rob Clark <robdclark@xxxxxxxxxxxx>
Link: https://lore.kernel.org/r/1623293391-17261-1-git-send-email-xiyuyang19@xxxxxxxxxxxx
Signed-off-by: Will Deacon <will@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/iommu/arm-smmu.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
index abf4cf285548..2185ea5191c1 100644
--- a/drivers/iommu/arm-smmu.c
+++ b/drivers/iommu/arm-smmu.c
@@ -1231,6 +1231,7 @@ static phys_addr_t arm_smmu_iova_to_phys_hard(struct iommu_domain *domain,
 	u64 phys;
 	unsigned long va, flags;
 	int ret, idx = cfg->cbndx;
+	phys_addr_t addr = 0;
 
 	ret = arm_smmu_rpm_get(smmu);
 	if (ret < 0)
@@ -1249,6 +1250,7 @@ static phys_addr_t arm_smmu_iova_to_phys_hard(struct iommu_domain *domain,
 		dev_err(dev,
 			"iova to phys timed out on %pad. Falling back to software table walk.\n",
 			&iova);
+		arm_smmu_rpm_put(smmu);
 		return ops->iova_to_phys(ops, iova);
 	}
 
@@ -1257,12 +1259,14 @@ static phys_addr_t arm_smmu_iova_to_phys_hard(struct iommu_domain *domain,
 	if (phys & CB_PAR_F) {
 		dev_err(dev, "translation fault!\n");
 		dev_err(dev, "PAR = 0x%llx\n", phys);
-		return 0;
+		goto out;
 	}
 
+	addr = (phys & GENMASK_ULL(39, 12)) | (iova & 0xfff);
+out:
 	arm_smmu_rpm_put(smmu);
 
-	return (phys & GENMASK_ULL(39, 12)) | (iova & 0xfff);
+	return addr;
 }
 
 static phys_addr_t arm_smmu_iova_to_phys(struct iommu_domain *domain,
-- 
2.30.2