cpufreq: exit() callback is optional

JIRA: https://issues.redhat.com/browse/RHEL-43846
CVE: CVE-2024-38615

commit b8f85833c05730d631576008daaa34096bc7f3ce
Author: Viresh Kumar viresh.kumar@linaro.org
Date: Fri Apr 12 11:19:20 2024 +0530

The exit() callback is optional and shouldn't be called without checking a valid pointer first.

Also, we must clear freq_table pointer even if the exit() callback isn't present.

Signed-off-by: Viresh Kumar viresh.kumar@linaro.org
Fixes: 91a12e91 ("cpufreq: Allow light-weight tear down and bring up of CPUs")
Fixes: f339f3541701 ("cpufreq: Rearrange locking in cpufreq_remove_dev()")
Reported-by: Lizhe sensor1010@163.com
Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com
Signed-off-by: Mark Langsdorf mlangsdo@redhat.com