[PATCH 5.13 099/351] iommu/arm-smmu: Fix arm_smmu_device refcount leak when arm_smmu_rpm_get fails

From: Greg Kroah-Hartman
Date: Mon Jul 19 2021 - 13:26:40 EST

From: Xiyu Yang <xiyuyang19@xxxxxxxxxxxx>

[ Upstream commit 1adf30f198c26539a62d761e45af72cde570413d ]

arm_smmu_rpm_get() invokes pm_runtime_get_sync(), which increases the
refcount of the "smmu" even though the return value is less than 0.

The reference counting issue happens in some error handling paths of
arm_smmu_rpm_get() in its caller functions. When arm_smmu_rpm_get()
fails, the caller functions forget to decrease the refcount of "smmu"
increased by arm_smmu_rpm_get(), causing a refcount leak.

Fix this issue by calling pm_runtime_resume_and_get() instead of
pm_runtime_get_sync() in arm_smmu_rpm_get(), which can keep the refcount
balanced in case of failure.

Signed-off-by: Xiyu Yang <xiyuyang19@xxxxxxxxxxxx>
Signed-off-by: Xin Tan <tanxin.ctf@xxxxxxxxx>
Link: https://lore.kernel.org/r/1623293672-17954-1-git-send-email-xiyuyang19@xxxxxxxxxxxx
Signed-off-by: Will Deacon <will@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
drivers/iommu/arm/arm-smmu/arm-smmu.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c b/drivers/iommu/arm/arm-smmu/arm-smmu.c
index 6f72c4d208ca..ee6cac9e7c02 100644
--- a/drivers/iommu/arm/arm-smmu/arm-smmu.c
+++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c
@@ -74,7 +74,7 @@ static bool using_legacy_binding, using_generic_binding;
static inline int arm_smmu_rpm_get(struct arm_smmu_device *smmu)
if (pm_runtime_enabled(smmu->dev))
- return pm_runtime_get_sync(smmu->dev);
+ return pm_runtime_resume_and_get(smmu->dev);

return 0;