CVE-2021-47327 Affecting kernel-rt-debug-modules-internal package, versions *

Note: Versions mentioned in the description apply only to the upstream kernel-rt-debug-modules-internal package and not the kernel-rt-debug-modules-internal package as distributed by Centos. See How to fix? for Centos:8 relevant fixed versions and status.

In the Linux kernel, the following vulnerability has been resolved:

iommu/arm-smmu: Fix arm_smmu_device refcount leak when arm_smmu_rpm_get fails

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.

• https://access.redhat.com/security/cve/CVE-2021-47327
• https://git.kernel.org/stable/c/1adf30f198c26539a62d761e45af72cde570413d
• https://git.kernel.org/stable/c/3761ae0d0e549f2acdaf11f49df4ed06d256b20f
• https://git.kernel.org/stable/c/c4007596fbdabc29f858dc2e1990858a146b60b2
• https://git.kernel.org/stable/c/fbf4daa6f4105e01fbd3868006f65c163365c1e3
• https://git.kernel.org/stable/c/fe92c058199067ae90cf2a901ddf3c271893557a