In the Linux kernel, the following vulnerability has been resolved: bpf, lockdown, audit: Fix buggy SELinux lockdown permission checks Commit 59438b46471a (security,lockdown,selinux: implement SELinux lockdown) added an implementation of the locked_down LSM hook to SELinux, with the aim to restrict which domains are allowed to perform operations that would breach lockdown. This is indirectly also getting audit subsystem involved to report events. The latter is problematic, as reported by Ondrej and Serhei, since it can bring down the whole system via audit: 1) The audit events that are triggered due to calls to security_locked_down() can OOM kill a machine, see below details [0]. 2) It also seems to be causing a deadlock via avc_has_perm()/slow_avc_audit() when trying to wake up kauditd, for example, when using trace_sched_switch() tracepoint, see details in [1]. Triggering this was not via some hypothetical corner case, but with existing tools like runqlat & runqslower from bcc, for example, which make use of this tracepoint. Rough call sequence goes like: rq_lock(rq) -> -------------------------+ trace_sched_switch() -> | bpf_prog_xyz() -> +-> deadlock selinux_lockdown() -> | audit_log_end() -> | wake_up_interruptible() -> | try_to_wake_up() -> | rq_lock(rq) --------------+ What\'s worse is that the intention of 59438b46471a to further restrict lockdown settings for specific applications in respect to the global lockdown policy is completely broken for BPF. The SELinux policy rule for the current lockdown check looks something like this: allow
Find out more about CVE-2021-47128 from the MITRE-CVE dictionary and NIST NVD
Login may be required to access defects or downloads.
Product Name | Status | Defect | Fixed | Downloads |
---|---|---|---|---|
Linux | ||||
Wind River Linux LTS 17 | Requires LTSS | -- | -- | -- |
Wind River Linux 8 | Requires LTSS | -- | -- | -- |
Wind River Linux 9 | Requires LTSS | -- | -- | -- |
Wind River Linux 7 | Requires LTSS | -- | -- | -- |
Wind River Linux LTS 21 | Fixed |
LIN1021-7781 |
10.21.20.21 | -- |
Wind River Linux LTS 22 | Not Vulnerable | -- | -- | -- |
Wind River Linux LTS 18 | Requires LTSS | -- | -- | -- |
Wind River Linux LTS 19 | Won't Fix | -- | -- | -- |
Wind River Linux CD release | N/A | -- | -- | -- |
Wind River Linux 6 | Requires LTSS | -- | -- | -- |
Wind River Linux LTS 23 | Not Vulnerable | -- | -- | -- |
VxWorks | ||||
VxWorks 7 | Not Vulnerable | -- | -- | -- |
VxWorks 6.9 | Not Vulnerable | -- | -- | -- |
Helix Virtualization Platform Cert Edition | ||||
Helix Virtualization Platform Cert Edition | Not Vulnerable | -- | -- | -- |
Product Name | Status | Defect | Fixed | Downloads |
---|