Important kernel security update: CVE-2017-12188 and other; Virtuozzo ReadyKernel patch 35.2 for Virtuozzo 7.0.4, 7.0.4 HF3, and 7.0.5

Issue date: 2017-10-23

Applies to: Virtuozzo 7.0

Virtuozzo Advisory ID: VZA-2017-098

1. Overview

The cumulative Virtuozzo ReadyKernel patch was updated with security and stability fixes. The patch applies to Virtuozzo kernels 3.10.0-514.16.1.vz7.30.10 (Virtuozzo 7.0.4), 3.10.0-514.16.1.vz7.30.15 (Virtuozzo 7.0.4 HF3), and 3.10.0-514.26.1.vz7.33.22 (Virtuozzo 7.0.5).

2. Security Fixes

[Important] Linux kernel built with the KVM virtualisation support (CONFIG_KVM), with nested virtualisation (nVMX) feature enabled (nested=1), is vulnerable to a stack buffer overflow issue. It could occur while traversing guest pagetable entries to resolve guest virtual address. A guest system could use this flaw to crash the host kernel resulting in DoS, or potentially execute arbitrary code on the host. (CVE-2017-12188)
[Moderate] A flaw was found in the Linux networking subsystem where a local attacker with CAP_NET_ADMIN capabilities could cause an out-of-bounds memory access by creating a smaller-than-expected ICMP header and sending to its destination via sendto(). (CVE-2016-8399)
[Moderate] It was found that in the Linux kernel through v4.14-rc5, bio_map_user_iov() and bio_unmap_user() in ‘block/bio.c’ do unbalanced pages refcounting if IO vector has small consecutive buffers belonging to the same page. bio_add_pc_page() merges them into one, but the page reference is never dropped, causing a memory leak and possible system lockup due to out-of-memory condition. (CVE-2017-12190)

3. Bug Fixes

It was discovered that the value of task->pids[type].pid was actually read twice in __task_pid_nr_ns() rather than only once, due to compiler optimizations. As a result, a race condition could happen and that value could become NULL between these reads, leading to a kernel crash (NULL pointer dereference). (PSBM-75247)
It was discovered that a specially crafted sequence of system calls could cause a kernel crash (general protection fault) in rt6_ifdown(). (PSBM-75641)

4. Installing the Update

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

5. References

The JSON file with the list of new and updated packages is available at JSON file.