CVE-2022-50491

/// Technical description

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

coresight: cti: Fix hang in cti_disable_hw()

cti_enable_hw() and cti_disable_hw() are called from an atomic context

so shouldn't use runtime PM because it can result in a sleep when

communicating with firmware.

Since commit 3c6656337852 ("Revert "firmware: arm_scmi: Add clock

management to the SCMI power domain""), this causes a hang on Juno when

running the Perf Coresight tests or running this command:

perf record -e cs_etm//u -- ls

This was also missed until the revert commit because pm_runtime_put()

was called with the wrong device until commit 692c9a499b28 ("coresight:

cti: Correct the parameter for pm_runtime_put")

With lock and scheduler debugging enabled the following is output:

coresight cti_sys0: cti_enable_hw -- dev:cti_sys0 parent: 20020000.cti

BUG: sleeping function called from invalid context at drivers/base/power/runtime.c:1151

in_atomic(): 1, irqs_disabled(): 128, non_block: 0, pid: 33

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References