Synopsis

Moderate: kernel security, bug fix, and enhancement update

Type/Severity

Security Advisory: Moderate

Topic

Updated kernel packages that fix multiple security issues, several bugs,
and add one enhancement are now available for Red Hat Enterprise Linux 6.

Red Hat Product Security has rated this update as having Moderate security
impact. Common Vulnerability Scoring System (CVSS) base scores, which give
detailed severity ratings, are available for each vulnerability from the
CVE links in the References section.

Description

The kernel packages contain the Linux kernel, the core of any Linux
operating system.

• A NULL pointer dereference flaw was found in the way the Linux kernel's

virtual console implementation handled reference counting when accessing
pseudo-terminal device files (/dev/pts/*). A local, unprivileged attacker
could use this flaw to crash the system. (CVE-2011-5321, Moderate)

• It was found that the Linux kernel's ping socket implementation did not

properly handle socket unhashing during spurious disconnects, which could
lead to a use-after-free flaw. On x86-64 architecture systems, a local user
able to create ping sockets could use this flaw to crash the system.
On non-x86-64 architecture systems, a local user able to create ping
sockets could use this flaw to escalate their privileges on the system.
(CVE-2015-3636, Moderate)

• An integer overflow flaw was found in the way the Linux kernel randomized

the stack for processes on certain 64-bit architecture systems, such as
x86-64, causing the stack entropy to be reduced by four. (CVE-2015-1593,
Low)

• A flaw was found in the way the Linux kernel's 32-bit emulation

implementation handled forking or closing of a task with an 'int80' entry.
A local user could potentially use this flaw to escalate their privileges
on the system. (CVE-2015-2830, Low)

• It was found that the Linux kernel's TCP/IP protocol suite implementation

for IPv6 allowed the Hop Limit value to be set to a smaller value than the
default one. An attacker on a local network could use this flaw to prevent
systems on that network from sending or receiving network packets.
(CVE-2015-2922, Low)

These updated kernel packages also include numerous bug fixes and one
enhancement. Space precludes documenting all of these changes in this
advisory. For information on the most significant of these changes, users
are directed to the following article on the Red Hat Customer Portal:

https://access.redhat.com/articles/1506133

All kernel users are advised to upgrade to these updated packages, which
contain backported patches to correct these issues and add this
enhancement. The system must be rebooted for this update to take effect.

Solution

Before applying this update, make sure all previously released errata
relevant to your system have been applied.

For details on how to apply this update, refer to:

https://access.redhat.com/articles/11258

Affected Products

• Red Hat Enterprise Linux Server 6 x86_64
• Red Hat Enterprise Linux Server 6 i386
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 6.6 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 6.6 i386
• Red Hat Enterprise Linux Server - Extended Update Support from RHUI 6.6 i386
• Red Hat Enterprise Linux Server - AUS 6.6 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 6 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 6 i386
• Red Hat Enterprise Linux Workstation 6 x86_64
• Red Hat Enterprise Linux Workstation 6 i386
• Red Hat Enterprise Linux Desktop 6 x86_64
• Red Hat Enterprise Linux Desktop 6 i386
• Red Hat Enterprise Linux for IBM z Systems 6 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 6.6 s390x
• Red Hat Enterprise Linux for Power, big endian 6 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 6.6 ppc64
• Red Hat Enterprise Linux for Scientific Computing 6 x86_64
• Red Hat Enterprise Linux Server from RHUI 6 x86_64
• Red Hat Enterprise Linux Server from RHUI 6 i386
• Red Hat Enterprise Linux Server - Extended Update Support from RHUI 6.6 x86_64
• Red Hat Enterprise Linux EUS Compute Node 6.6 x86_64
• Red Hat Enterprise Linux Server - TUS 6.6 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support (for IBM z Systems) 6 s390x

Fixes

• BZ - 1192519 - CVE-2015-1593 kernel: Linux stack ASLR implementation Integer overflow
• BZ - 1201887 - CVE-2011-5321 Kernel: tty: driver reference leakage in tty_open
• BZ - 1203712 - CVE-2015-2922 kernel: denial of service (DoS) attack against IPv6 network stacks due to improper handling of Router Advertisements.
• BZ - 1208598 - CVE-2015-2830 kernel: int80 fork from 64-bit tasks mishandling
• BZ - 1218074 - CVE-2015-3636 kernel: ping sockets: use-after-free leading to local privilege escalation

CVEs

• CVE-2015-2830
• CVE-2015-1593
• CVE-2011-5321
• CVE-2015-2922
• CVE-2015-3636

References