CVE-2021-47421

A moderate-impact denial-of-service flaw was found in the Linux kernel's AMD GPU (amdgpu) driver, which is shipped in the kernel and kernel-rt packages of Red Hat Enterprise Linux and in Red Hat's hosted OpenShift offerings (ARO and OSD) through the underlying Red Hat Enterprise Linux kernel. During PCI error recovery, when a device's PCI channel is in the frozen state, the amdgpu device resume path can improperly release a lock that was not acquired. This improper synchronization causes subsequent threads that attempt to acquire the associated read locks to deadlock, rendering the graphics subsystem or the system unresponsive. A local attacker able to trigger the required PCI error recovery conditions could exploit this flaw to cause a denial of service; confidentiality and integrity are not affected. Because the flaw requires local access and uncommon PCI error recovery conditions and only affects availability, Red Hat assesses it as Moderate (CVSS 3.1 score 4.7). This is lower than the upstream CVE record's score of 7.8, which assumes a compromise of confidentiality and integrity that the technical evidence does not support. Within Red Hat's product scope, the Red Hat Enterprise Linux 8 kernel is recorded as affected with the fix delegated to the kernel maintenance team, and the Red Hat Enterprise Linux 9 kernel and kernel-rt update-stream affects carry a delegated not-affected outcome because the correcting change is already present in those kernels. Several Red Hat Enterprise Linux kernel-rt update streams, Red Hat Enterprise Linux 6 Extended Lifecycle Support, and Fedora are recorded as not affected.