ALAS-2024-493

Amazon Linux 2023 Security Advisory: ALAS-2024-493
Advisory Release Date: 2024-01-19 01:31 Pacific
Advisory Updated Date: 2024-01-22 20:30 Pacific
Severity: Important
Issue Overview:

When a router encounters an IPv6 packet too big to transmit to the next-hop, it returns an ICMP6 "Packet Too Big" (PTB) message to the sender. The sender caches this updated Maximum Transmission Unit (MTU) so it knows not to exceed this value when subsequently routing to the same host.

In Linux kernels prior to 6.3, garbage collection is run on the IPv6 Destination Route Cache if the number of entries exceeds a threshold when adding the destination to the cache. This garbage collection examines every entry in the cache while holding a lock. In these affected kernel versions, a flood of the IPv6 ICMP6 PTB messages could cause high lock contention and increased CPU usage, leading to a Denial-of-Service.

The fix backports the garbage collection improvements from Linux kernel 6.3 by bringing the IPv6 code closer to the IPv4 code, which does not have this issue.

Patch: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit?id=af6d10345ca76670c1b7c37799f0d5576ccef277 (CVE-2023-52340)


Affected Packages:

kernel


Issue Correction:
Run dnf update kernel --releasever 2023.3.20240122 to update your system.

New Packages:
aarch64:
    python3-perf-debuginfo-6.1.66-93.164.amzn2023.aarch64
    kernel-modules-extra-common-6.1.66-93.164.amzn2023.aarch64
    perf-6.1.66-93.164.amzn2023.aarch64
    perf-debuginfo-6.1.66-93.164.amzn2023.aarch64
    python3-perf-6.1.66-93.164.amzn2023.aarch64
    kernel-tools-debuginfo-6.1.66-93.164.amzn2023.aarch64
    kernel-modules-extra-6.1.66-93.164.amzn2023.aarch64
    kernel-libbpf-static-6.1.66-93.164.amzn2023.aarch64
    kernel-tools-devel-6.1.66-93.164.amzn2023.aarch64
    bpftool-debuginfo-6.1.66-93.164.amzn2023.aarch64
    kernel-libbpf-6.1.66-93.164.amzn2023.aarch64
    kernel-livepatch-6.1.66-93.164-1.0-0.amzn2023.aarch64
    kernel-tools-6.1.66-93.164.amzn2023.aarch64
    kernel-libbpf-devel-6.1.66-93.164.amzn2023.aarch64
    kernel-headers-6.1.66-93.164.amzn2023.aarch64
    bpftool-6.1.66-93.164.amzn2023.aarch64
    kernel-debuginfo-6.1.66-93.164.amzn2023.aarch64
    kernel-6.1.66-93.164.amzn2023.aarch64
    kernel-debuginfo-common-aarch64-6.1.66-93.164.amzn2023.aarch64
    kernel-devel-6.1.66-93.164.amzn2023.aarch64

src:
    kernel-6.1.66-93.164.amzn2023.src

x86_64:
    kernel-libbpf-devel-6.1.66-93.164.amzn2023.x86_64
    kernel-modules-extra-6.1.66-93.164.amzn2023.x86_64
    bpftool-6.1.66-93.164.amzn2023.x86_64
    python3-perf-6.1.66-93.164.amzn2023.x86_64
    kernel-livepatch-6.1.66-93.164-1.0-0.amzn2023.x86_64
    kernel-tools-6.1.66-93.164.amzn2023.x86_64
    perf-debuginfo-6.1.66-93.164.amzn2023.x86_64
    kernel-libbpf-static-6.1.66-93.164.amzn2023.x86_64
    perf-6.1.66-93.164.amzn2023.x86_64
    python3-perf-debuginfo-6.1.66-93.164.amzn2023.x86_64
    kernel-modules-extra-common-6.1.66-93.164.amzn2023.x86_64
    bpftool-debuginfo-6.1.66-93.164.amzn2023.x86_64
    kernel-libbpf-6.1.66-93.164.amzn2023.x86_64
    kernel-tools-debuginfo-6.1.66-93.164.amzn2023.x86_64
    kernel-tools-devel-6.1.66-93.164.amzn2023.x86_64
    kernel-debuginfo-6.1.66-93.164.amzn2023.x86_64
    kernel-headers-6.1.66-93.164.amzn2023.x86_64
    kernel-6.1.66-93.164.amzn2023.x86_64
    kernel-debuginfo-common-x86_64-6.1.66-93.164.amzn2023.x86_64
    kernel-devel-6.1.66-93.164.amzn2023.x86_64

Additional References

Red Hat: CVE-2023-52340

Mitre: CVE-2023-52340