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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’.

Dec 12, 2024
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