CVE-2021-47187: linux kernel vulnerability

What is known

In the Linux kernel, the following vulnerability has been resolved: arm64: dts: qcom: msm8998: Fix CPU/L2 idle state latency and residency The entry/exit latency and minimum residency in state for the idle states of MSM8998 were ..bad: first of all, for all of them the timings were written for CPU sleep but the min-residency-us param was miscalculated (supposedly, while porting this from downstream); Then, the power collapse states are setting PC on both the CPU cluster *and* the L2 cache, which have different timings: in the specific case of L2 the times are higher so these ones should be taken into account instead of the CPU ones. This parameter misconfiguration was not giving particular issues because on MSM8998 there was no CPU scaling at all, so cluster/L2 power collapse was rarely (if ever) hit. When CPU scaling is enabled, though, the wrong timings will produce SoC unstability shown to the user as random, apparently error-less, sudden reboots and/or lockups. This set of parameters are stabilizing the SoC when CPU scaling is ON and when power collapse is frequently hit.

Business impact

Successful exploitation of CVE-2021-47187, a medium vulnerability (CVSS 5.5) affecting linux kernel, may affect the confidentiality, integrity or availability of the vulnerable environment. The exact impact depends on the installed version, exposed interfaces and deployment configuration.

Recommended administrator action

Confirm whether linux kernel is present and compare installed versions with the vendor advisory and NVD record. Apply the vendor patch or documented mitigation; until remediation is complete, reduce exposure of affected interfaces, review relevant logs and monitor for indicators of exploitation. DataHouse can support version verification, managed patching, network exposure reduction, log review and backup validation for dedicated, cloud and colocated environments.

Sources

• NVD
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