A deadlock flaw was found in the Linux kernel’s BPF subsystem. The fail happens in the function sock_hash_delete_elem. This flaw allows a local user to potentially crash the system.

Mitigation

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 or 9 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 cannot use eBPF, mitigating the flaw.

A kernel update will be required to mitigate the flaw for the root or users with CAP_SYS_ADMIN capabilities.

Note: A fix for this CVE may be backported as a part of one of the future BPF subsystem rebases.