CVE-2021-45402

A memory leak flaw was found in the Linux kernel’s BPF subsystem in the way a user triggers the check_alu_op function of the BPF verifier. This flaw allows a local user to obtain unauthorized memory access or potentially crash the system.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

The default Red Hat Enterprise Linux kernel prevents unprivileged users from being able to use eBPF by the kernel.unprivileged_bpf_disabled sysctl. This would require a privileged user with CAP_SYS_ADMIN or root to be able to abuse this flaw reducing its attack space.

For the Red Hat Enterprise Linux 7, the eBPF for unprivileged users is always disabled. For the Red Hat Enterprise Linux 8 to confirm the current state, inspect the sysctl with the command:

cat /proc/sys/kernel/unprivileged_bpf_disabled

The setting of 1 would mean that unprivileged users can not use eBPF, mitigating the flaw.