CVE-2021-0941

An out-of-bounds (OOB) memory access flaw was found in net/core/filter.c in __bpf_skb_max_len in the Linux kernel. A missing sanity check to the current MTU check may allow a local attacker with special user privilege to gain access to out-of-bounds memory leading to a system crash or a leak of internal kernel information.

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.

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

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.

Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.