Kernel security update: Virtuozzo ReadyKernel patch 49.0 for Virtuozzo 7.0.1, 7.0.3, 7.0.5, 7.0.6, and 7.0.6 HF3

Issue date: 2018-05-07

Applies to: Virtuozzo 7.0

Virtuozzo Advisory ID: VZA-2018-024

1. Overview

The cumulative Virtuozzo ReadyKernel patch was updated with security and stability fixes. The patch applies to Virtuozzo 7.0 kernels 3.10.0-327.42.0.vz7.18.7 (7.0.1), 3.10.0-327.42.0.vz7.20.18 (7.0.3), 3.10.0-514.26.1.vz7.33.22 (7.0.5), 3.10.0-693.1.1.vz7.37.30 (7.0.6), and 3.10.0-693.11.6.vz7.40.4 (7.0.6 HF3). NOTE: No more patches are planned for kernel 3.10.0-327.47.0.vz7.18.7, support for which ends with this update.

2. Security Fixes

  • [Moderate] It was discovered that nfnl_cthelper_list structure was accessible to any user with CAP_NET_ADMIN capability in a network namespace. An unprivileged local user could exploit that to affect netfilter conntrack helpers on the host. (CVE-2017-17448)

  • [Moderate] It was discovered that a nlmon link inside a child network namespace was not restricted to that namespace. An unprivileged local user could exploit that to monitor system-wide netlink activity. (CVE-2017-17449)

  • [Low] It was discovered that xt_osf_fingers data structure was accessible from any network namespace. This allowed unprivileged local users to bypass intended access restrictions and modify the system-wide OS fingerprint list used by specific iptables rules. (CVE-2017-17450)

  • [Moderate] The KEYS subsystem omitted an access-control check when writing a key to the default keyring of the current task, allowing a local user to bypass security checks for the keyring. This compromised the validity of the keyring for those who relied on it. (CVE-2017-17807)

  • [Moderate] If ‘dccp_ipv6’ module was loaded on the host, a local unprivileged user could trigger a kernel crash in dccp_write_xmit() or inet_csk_get_port() using a specially crafted sequence of system calls. (PSBM-83692)

3. Bug Fixes

  • If the kernel failed to create an IPv6 socket, for example, due to cgroup.memsw limit, it would crash in ip6mr_sk_done() when trying to clean up multicast routes. (PSBM-83474)

  • It was discovered that the BUG_ON() check in move_freepages() did not verify that the relevant memory pages were valid. The kernel could crash as a result. (PSBM-83746)

  • It was discovered that clone_mnt() did not clear MNT_INTERNAL flag for the internal mounts. As a result, the kernel could crash due to a stack overflow if lots of bind mounts of /proc//ns/ were created in a new namespace. (PSBM-83874)

4. Installing the Update

Download, install, and instantly apply the patch to the current kernel by running ‘readykernel update’.