RHSA-2015:1565 - Security Advisory

Topic

Updated kernel-rt packages that fix multiple security issues, several bugs,
and add various enhancements are now available for Red Hat Enterprise
Linux 7.

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

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

netfilter connection tracking implementation loaded extensions. An attacker
on a local network could potentially send a sequence of specially crafted
packets that would initiate the loading of a large number of extensions,
causing the targeted system in that network to crash. (CVE-2014-9715,
Moderate)

• A stack-based buffer overflow flaw was found in the Linux kernel's early

load microcode functionality. On a system with UEFI Secure Boot enabled, a
local, privileged user could use this flaw to increase their privileges to
the kernel (ring0) level, bypassing intended restrictions in place.
(CVE-2015-2666, 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)

• 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)

Red Hat would like to thank Nathan Hoad for reporting the CVE-2014-9715
issue.

The kernel-rt packages have been upgraded to version 3.10.0-229.11.1, which
provides a number of bug fixes and enhancements over the previous version,
including:

• drbg: Add stdrng alias and increase priority
• seqiv / eseqiv / chainiv: Move IV seeding into init function
• ipv4: kABI fix for 0bbf87d backport
• ipv4: Convert ipv4.ip_local_port_range to be per netns
• libceph: tcp_nodelay support
• ipr: Increase default adapter init stage change timeout
• fix use-after-free bug in usb_hcd_unlink_urb()
• libceph: fix double __remove_osd() problem
• ext4: fix data corruption caused by unwritten and delayed extents
• sunrpc: Add missing support for RPC_CLNT_CREATE_NO_RETRANS_TIMEOUT
• nfs: Fixing lease renewal (Benjamin Coddington)
• control hard lockup detection default
• Fix print-once on enable
• watchdog: update watchdog_thresh properly and watchdog attributes

atomically

• module: Call module notifier on failure after complete_formation()

(BZ#1234470)

This update also fixes the following bugs:

• The megasas driver used the smp_processor_id() function within a

preemptible context, which caused warning messages to be returned to the
console. The function has been changed to raw_smp_processor_id() so that a
lock is held while getting the processor ID. As a result, correct
operations are now allowed without any console warnings being produced.
(BZ#1235304)

• In the NFSv4 file system, non-standard usage of the

write_seqcount_{begin,end}() functions were used, which caused the realtime
code to try to sleep while locks were held. As a consequence, the
"scheduling while atomic" error messages were returned. The underlying
source code has been modified to use the __write_seqcount_{begin,end}()
functions that do not hold any locks, allowing correct execution of
realtime. (BZ#1235301)

All kernel-rt users are advised to upgrade to these updated packages, which
correct these issues and add these enhancements. 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 for Real Time 7 x86_64
• Red Hat Enterprise Linux for Real Time for x86_64 - Extended Life Cycle Support 7 x86_64

Fixes

• BZ - 1203712 - CVE-2015-2922 kernel: denial of service (DoS) attack against IPv6 network stacks due to improper handling of Router Advertisements.
• BZ - 1204722 - CVE-2015-2666 kernel: execution in the early microcode loader
• BZ - 1208684 - CVE-2014-9715 kernel: netfilter connection tracking extensions denial of service
• BZ - 1218074 - CVE-2015-3636 kernel: ping sockets: use-after-free leading to local privilege escalation
• BZ - 1234470 - kernel-rt: update to the RHEL7.1.z batch 4 source tree

CVEs

• CVE-2014-9715
• CVE-2015-2666
• CVE-2015-2922
• CVE-2015-3636

References

• http://www.redhat.com/security/updates/classification/#normal