CVE-2024-26589

A vulnerability has been identified in the Linux kernel's Berkeley Packet Filter (BPF) subsystem. The flaw resides within the handling of PTR_TO_FLOW_KEYS (pointer to flow keys) in the check_flow_keys_access() function.

Specifically, while fixed offsets are validated for PTR_TO_FLOW_KEYS, the system currently fails to prohibit variable offset pointer arithmetic for this pointer type. This oversight allows a malicious or specially crafted BPF program to perform an unchecked variable offset addition to the flow keys pointer. This results in an out-of-bounds memory access, which can lead to a kernel crash. This issue directly impacts system availability by causing a denial of service.

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 Red Hat Enterprise Linux 8 to confirm the current state, inspect the sysctl with the command:

# cat /proc/sys/kernel/unprivileged_bpf_disabled

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

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.

No mitigation is currently available for this vulnerability. Make sure to perform the updates as they become available.