Important kernel security update: CVE-2017-8824 and other; Virtuozzo ReadyKernel patch 39.1 for Virtuozzo 7.0.6¶
Issue date: 2017-12-11
Applies to: Virtuozzo 7.0
Virtuozzo Advisory ID: VZA-2017-111
1. Overview¶
The cumulative Virtuozzo ReadyKernel patch was updated with security and stability fixes. The patch applies to Virtuozzo kernel 3.10.0-693.1.1.vz7.37.30 (Virtuozzo 7.0.6).
2. Security Fixes¶
[Important] dccp_disconnect() set the socket state to DCCP_CLOSED but did not properly free some of the resources associated with that socket. This could result in a use-after-free and could potentially allow an attacker to escalate their privileges. (CVE-2017-8824)
[Important] The Linux kernel is vulnerable to a use-after-free issue. It could occur while closing a xfrm netlink socket, in xfrm_dump_policy_done. A user/process could use this flaw to potentially escalate their privileges on a system. (CVE-2017-16939)
[Important] A flaw was found in the patches used to fix the ‘Dirty COW’ vulnerability (CVE-2016-5195). An attacker, able to run local code, can exploit a race condition in transparent huge pages to modify usually read-only huge pages. (CVE-2017-1000405)
[Moderate] A vulnerability was found in the kernel virtualization module (KVM) for the Intel processors. A guest system could flood the I/O port 0x80 with write requests, which could crash the host kernel, resulting in DoS. (CVE-2017-1000407)
3. Bug Fixes¶
Many of the issues that BUG_ON()s were supposed to catch in tcache were not serious enough to crash the kernel. A warning will now be output in such cases instead. (PSBM-77154)
FUSE: improve performance of splice() operation in case of heavily fragmented memory. (PSBM-77949)
When there were more than two users of a page, __tcache_page_tree_delete() failed to freeze it. The page would never be invalidated and tcache_node->nr_pages would never be decremented. A kernel warning would be output as a result. (PSBM-78354)
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 http://docs.virtuozzo.com/vza/VZA-2017-111.json.