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.
Exploits
Credits
Red Hat would like to thank Hsin-Wei Hung (University of California, Irvine) for reporting this issue.