CVE-2022-50494

/// Technical description

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

thermal: intel_powerclamp: Use get_cpu() instead of smp_processor_id() to avoid crash

When CPU 0 is offline and intel_powerclamp is used to inject

idle, it generates kernel BUG:

BUG: using smp_processor_id() in preemptible [00000000] code: bash/15687

caller is debug_smp_processor_id+0x17/0x20

CPU: 4 PID: 15687 Comm: bash Not tainted 5.19.0-rc7+ #57

Call Trace:

<TASK>

dump_stack_lvl+0x49/0x63

dump_stack+0x10/0x16

check_preemption_disabled+0xdd/0xe0

debug_smp_processor_id+0x17/0x20

powerclamp_set_cur_state+0x7f/0xf9 [intel_powerclamp]

...

...

Here CPU 0 is the control CPU by default and changed to the current CPU,

if CPU 0 offlined. This check has to be performed under cpus_read_lock(),

hence the above warning.

Use get_cpu() instead of smp_processor_id() to avoid this BUG.

[ rjw: Subject edits ]

/// 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