A flaw in the Linux kernel allows a privileged BPF program to obtain sensitive information from kernel memory via a Speculative Store Bypass side-channel in the eBPF subsystem

Mitigation

The default Red Hat Enterprise Linux kernel setting prevents unprivileged users from being able to use eBPF via the kernel.unprivileged_bpf_disabled sysctl. As such, exploiting this issue would require a privileged user with CAP_SYS_ADMIN or root.

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 (default) would mean that unprivileged users cannot use eBPF. Otherwise, to disable eBPF for unprivileged users, add:

kernel.unprivileged_bpf_disabled = 1

To the file "/etc/sysctl.d/disable-ebpf.conf"

Then running the following command as root:

sudo sysctl --system