CVE-2021-46971

Summary

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.

Affected Software

VendorProductVersion RangeStatus
LinuxLinuxb0c8fdc7fdb77586c3d1937050925b960743306e < b246759284d6a2bc5b6f1009caeeb3abce2ec9ffaffected
LinuxLinuxb0c8fdc7fdb77586c3d1937050925b960743306e < 4348d3b5027bc3ff6336368b6c60605d4ef8e1ceaffected
LinuxLinuxb0c8fdc7fdb77586c3d1937050925b960743306e < f5809ca4c311b71bfaba6d13f4e39eab0557895eaffected
LinuxLinuxb0c8fdc7fdb77586c3d1937050925b960743306e < c7b0208ee370b89d20486fae71cd9abb759819c1affected
LinuxLinuxb0c8fdc7fdb77586c3d1937050925b960743306e < 08ef1af4de5fe7de9c6d69f1e22e51b66e385d9baffected
LinuxLinux5.4affected
LinuxLinux0 < 5.4unaffected
LinuxLinux5.4.117 <= 5.4.*unaffected
LinuxLinux5.10.35 <= 5.10.*unaffected
LinuxLinux5.11.19 <= 5.11.*unaffected
LinuxLinux5.12.2 <= 5.12.*unaffected
LinuxLinux5.13 <= *unaffected

Weaknesses

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: no
    • Technical Impact: partial

CVE Program Container

Additional References

References