CVE-2021-47327

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> iommu/arm-smmu: Fix arm_smmu_device refcount leak when arm_smmu_rpm_get fails<br /> <br /> arm_smmu_rpm_get() invokes pm_runtime_get_sync(), which increases the<br /> refcount of the "smmu" even though the return value is less than 0.<br /> <br /> The reference counting issue happens in some error handling paths of<br /> arm_smmu_rpm_get() in its caller functions. When arm_smmu_rpm_get()<br /> fails, the caller functions forget to decrease the refcount of "smmu"<br /> increased by arm_smmu_rpm_get(), causing a refcount leak.<br /> <br /> Fix this issue by calling pm_runtime_resume_and_get() instead of<br /> pm_runtime_get_sync() in arm_smmu_rpm_get(), which can keep the refcount<br /> balanced in case of failure.