Red Hat Security Advisory: kernel security, bug fix, and enhancement update

Important

Linux kernel built with the KVM visualization support (CONFIG_KVM), with nested visualization (nVMX) feature enabled (nested=1), is vulnerable to a crash due to disabled external interrupts. As L2 guest could access (r/w) hardware CR8 register of the host(L0). In a nested visualization setup, L2 guest user could use this flaw to potentially crash the host(L0) resulting in DoS.

CWE-284 - Improper Access Control

A use-after-free vulnerability was found in a network namespaces code affecting the Linux kernel since v4.0-rc1 through v4.15-rc5. The function get_net_ns_by_id() does not check for the net::count value after it has found a peer network in netns_ids idr which could lead to double free and memory corruption. This vulnerability could allow an unprivileged local user to induce kernel memory corruption on the system, leading to a crash. Due to the nature of the flaw, privilege escalation cannot be fully ruled out, although it is thought to be unlikely.

CWE-362 - Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

A flaw was found in the implementation of associative arrays where the add_key systemcall and KEYCTL_UPDATE operations allowed for a NULL payload with a nonzero length. When accessing the payload within this length parameters value, an unprivileged user could trivially cause a NULL pointer dereference (kernel oops).

CWE-476 - NULL Pointer Dereference