iommu/arm-smmu: Fix arm_smmu_device refcount leak in address translation

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@fudan.edu.cn>
Signed-off-by: Xin Tan <tanxin.ctf@gmail.com>
Reviewed-by: Rob Clark <robdclark@chromium.org>
Link: https://lore.kernel.org/r/1623293391-17261-1-git-send-email-xiyuyang19@fudan.edu.cn
Signed-off-by: Will Deacon <will@kernel.org>

diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c b/drivers/iommu/arm/arm-smmu/arm-smmu.c
index 5de5cf5..22be819 100644 (file)
--- a/drivers/iommu/arm/arm-smmu/arm-smmu.c
+++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c
@@ -1271,6 +1271,7 @@ 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)
@@ -1290,6 +1291,7 @@ 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);
        }
 
@@ -1298,12 +1300,14 @@ static phys_addr_t arm_smmu_iova_to_phys_hard(struct iommu_domain *domain,
        if (phys & ARM_SMMU_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,