CVE-2021-46971

In the Linux kernel, the following vulnerability has been resolved:
perf/core: Fix unconditional security_locked_down() call Currently, the
lockdown state is queried unconditionally, even though its result is used
only if the PERF_SAMPLE_REGS_INTR bit is set in attr.sample_type. While
that doesn’t matter in case of the Lockdown LSM, it causes trouble with the
SELinux’s lockdown hook implementation. SELinux implements the locked_down
hook with a check whether the current task’s type has the corresponding
“lockdown” class permission (“integrity” or “confidentiality”) allowed in
the policy. This means that calling the hook when the access control
decision would be ignored generates a bogus permission check and audit
record. Fix this by checking sample_type first and only calling the hook
when its result would be honored.

Notes