RHSA-2015:1583 - Security Advisory

Topic

Updated kernel packages that fix one security issue and several bugs are
now available for Red Hat Enterprise Linux 6.5 Extended Update Support.

Red Hat Product Security has rated this update as having Moderate security
impact. A Common Vulnerability Scoring System (CVSS) base score, which
gives a detailed severity rating, is available from the CVE link in the
References section.

Description

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

• 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)

This update also fixes the following bugs:

• Previously, the bridge device did not propagate VLAN information to its

ports and Generic Receive Offload (GRO) information to devices that sit on
top. This resulted in lower receive performance of VLANs over bridge
devices because GRO was not enabled. An attempt to resolve this problem was
made with BZ#858198 by introducing a patch that allows VLANs to be
registered with the participating bridge ports and adds GRO to the bridge
device feature set, however, that attempt introduced a number of
regressions, which broke the vast majority of stacked setups involving
bridge devices and VLANs. This update reverts the patch provided by
BZ#858198 and removes support for this capability. (BZ#1131697)

• The backlog data could previously not be consumed when the

audit_log_start() function was running even if audit_log_start() called the
wait_for_auditd() function to consume it. As only auditd could consume the
backlog data, audit_log_start() terminated unexpectedly. Consequently, the
system became unresponsive until the backlog timeout was up again.
With this update, audit_log_start() no longer terminates and the system
shuts down and reboots gracefully in a timely manner. (BZ#1140490)

• This update introduces a set of patches with a new VLAN model to conform

to upstream standards. In addition, this set of patches fixes other issues
such as transmission of Internet Control Message Protocol (ICMP) fragments.
(BZ#1173560)

• Due to a bug in the audit code, a kernel panic occurred in the

tasklist_lock variable if SELinux was in permissive or enforcing mode.
A patch has been applied to fix this bug, and the operating system now
continues to work normally. (BZ#1236103)

• If a server returned an empty or malformed READDIR response, the NFS

client could previously terminate unexpectedly while attempting to decode
that response. This update uses the response size to determine if existing
pages of data are available for decoding, and the client only decodes the
responses if they exist. As a result, the NFS client no longer attempts to
decode pages of data that may not exist, and the aforementioned crash is
thus avoided. (BZ#1232133)

• Previously, if a slave device had a receive handler registered, then an

error unwind of bonding device enslave function became broken, which led to
a kernel oops. This update detaches the slave in the unwind path, and the
aforementioned oops no longer occurs. (BZ#1222482)

• Due to bad memory or memory corruption, an isolated BUG_ON(mm->nr_ptes)

was sometimes reported, indicating that not all the page tables allocated
could be found and freed when the exit_mmap() function cleared the user
address space. As a consequence, a kernel panic occurred. To fix this bug,
the BUG_ON() function has been replaced by WARN_ON(), which prevents the
kernel from panicking in the aforementioned situation. (BZ#1235930)

All kernel users are advised to upgrade to these updated packages, which
contain backported patches to correct these issues. 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 x86_64 - Extended Update Support 6.5 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 6.5 i386
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 6.5 s390x
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 6.5 ppc64
• Red Hat Enterprise Linux Server - Extended Update Support from RHUI 6.5 x86_64
• Red Hat Enterprise Linux Server - Extended Update Support from RHUI 6.5 i386
• Red Hat Enterprise Linux EUS Compute Node 6.5 x86_64
• Red Hat Enterprise Linux Server - AUS 6.5 x86_64
• Red Hat Enterprise Linux Server - TUS 6.5 x86_64

Fixes

• BZ - 1218074 - CVE-2015-3636 kernel: ping sockets: use-after-free leading to local privilege escalation

CVEs

• CVE-2015-3636

References

• https://access.redhat.com/security/updates/classification/#moderate