RHSA-2013:0662 - Security Advisory

Topic

Updated kernel packages that fix one security issue and several bugs are
now available for Red Hat Enterprise Linux 6.3 Extended Update Support.

The Red Hat Security Response Team has rated this update as having
important 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.

This update fixes the following security issue:

• A race condition was found in the way the Linux kernel's ptrace

implementation handled PTRACE_SETREGS requests when the debuggee was woken
due to a SIGKILL signal instead of being stopped. A local, unprivileged
user could use this flaw to escalate their privileges. (CVE-2013-0871,
Important)

This update also fixes the following bugs:

• Previously, init scripts were unable to set the MAC address of the master

interface properly because it was overwritten by the first slave MAC
address. To avoid this problem, this update re-introduces the check for an
unassigned MAC address before setting the MAC address of the first slave
interface as the MAC address of the master interface. (BZ#908735)

• When using transparent proxy (TProxy) over IPv6, the kernel previously

created neighbor entries for local interfaces and peers that were not
reachable directly. This update corrects this problem and the kernel no
longer creates invalid neighbor entries. (BZ#909158)

• Due to the incorrect validation of a pointer dereference in the

d_validate() function, running a command such as ls or find on the
MultiVersion File System (MVFS), used by IBM Rational ClearCase, for
example, could trigger a kernel panic. This update modifies d_validate() to
verify the parent-child dentry relationship by searching through the
parent's d_child list. The kernel no longer panics in this situation.
(BZ#915582)

• A previously backported patch introduced usage of the page_descs length

field but did not set the page data length for the FUSE page descriptor.
This code path can be exercised by a loopback device (pagecache_write_end)
if used over FUSE. As a result, fuse_copy_page does not copy page data from
the page descriptor to the user-space request buffer and the user space can
see uninitialized data. This could previously lead to file system data
corruption. This problem has been fixed by setting the page_descs length
prior to submitting the requests, and FUSE therefore provides correctly
initialized data. (BZ#916956)

Users should upgrade to these updated packages, which contain backported
patches to resolve 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.

This update is available via the Red Hat Network. Details on how to
use the Red Hat Network to apply this update are available at
https://access.redhat.com/knowledge/articles/11258

To install kernel packages manually, use "rpm -ivh [package]". Do not
use "rpm -Uvh" as that will remove the running kernel binaries from
your system. You may use "rpm -e" to remove old kernels after
determining that the new kernel functions properly on your system.

Affected Products

• Red Hat Enterprise Linux for x86_64 - Extended Update Support 6.3 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 6.3 i386
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 6.3 s390x
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 6.3 ppc64
• Red Hat Enterprise Linux Server - Extended Update Support from RHUI 6.3 x86_64
• Red Hat Enterprise Linux Server - Extended Update Support from RHUI 6.3 i386

Fixes

• BZ - 911937 - CVE-2013-0871 kernel: race condition with PTRACE_SETREGS

CVEs

• CVE-2013-0871

References

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