Subject: [ASA-201702-17] linux: multiple issues

Arch Linux Security Advisory ASA-201702-17
==========================================

Severity: High
Date    : 2017-02-22
CVE-ID  : CVE-2016-9588 CVE-2016-10088 CVE-2017-5986 CVE-2017-6074
Package : linux
Type    : multiple issues
Remote  : No
Link    : https://security.archlinux.org/AVG-178

Summary
=======

The package linux before version 4.9.11-1 is vulnerable to multiple
issues including privilege escalation and denial of service.

Resolution
==========

Upgrade to 4.9.11-1.

# pacman -Syu "linux>=4.9.11-1"

The problems have been fixed upstream in version 4.9.11.

Workaround
==========

None.

Description
===========

- CVE-2016-9588 (denial of service)

Linux kernel built with the KVM visualization support (CONFIG_KVM),
with nested visualization(nVMX) feature enabled(nested=1), is
vulnerable to an uncaught exception issue. It could occur if an L2
guest was to throw an exception which is not handled by an L1 guest.

- CVE-2016-10088 (privilege escalation)

The sg implementation in the Linux kernel through 4.9 does not properly
restrict write operations in situations where the KERNEL_DS option is
set, which allows local users to read or write to arbitrary kernel
memory locations or cause a denial of service (use-after-free) by
leveraging access to a /dev/sg device, related to block/bsg.c and
drivers/scsi/sg.c. NOTE: this vulnerability exists because of an
incomplete fix for CVE-2016-9576.

- CVE-2017-5986 (denial of service)

It was reported that with Linux kernel, earlier than version v4.10-rc8,
an application may trigger a BUG_ON in sctp_wait_for_sndbuf if the
socket tx buffer is full, a thread is waiting on it to queue more data,
and meanwhile another thread peels off the association being used by
the first thread. This issue may then lead to a segmentation fault
resulting in denial of service.

- CVE-2017-6074 (privilege escalation)

A use-after-free vulnerability has been discovered in the DCCP
implementation in the Linux kernel. The dccp_rcv_state_process function
in net/dccp/input.c in the Linux kernel through 4.9.11 mishandles
DCCP_PKT_REQUEST packet data structures in the LISTEN state. A local
unprivileged user could use this flaw to alter the kernel memory,
allowing them to escalate their privileges on the system via an
application that makes an IPV6_RECVPKTINFO setsockopt system call.

Impact
======

A local unprivileged attacker is able to perform a denial of service
attack or escalate their privileges on the system.

References
==========

https://github.com/torvalds/linux/commit/2dcab598484185dea7ec22219c76dcdd59e3cb90
http://seclists.org/oss-sec/2017/q1/432
https://github.com/torvalds/linux/commit/5edabca9d4cff7f1f2b68f0bac55ef99d9798ba4
https://patchwork.ozlabs.org/patch/728808/
https://security.archlinux.org/CVE-2016-9588
https://security.archlinux.org/CVE-2016-10088
https://security.archlinux.org/CVE-2017-5986
https://security.archlinux.org/CVE-2017-6074