CVE-2022-50494 — thermal: intel_powerclamp: Use get_cpu() instead of smp_processor_id() to avoid crash

Affected: Linux

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 ]

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CVE-2022-50494 — thermal: intel_powerclamp: Use get_cpu() instead of smp_processor_id() to avoid crash