RHSA-2011:1212 - Security Advisory

Topic

Updated kernel packages that fix multiple security issues and several bugs
are now available for Red Hat Enterprise Linux 5.

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

This update fixes the following security issues:

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

Control Transmission Protocol (SCTP) implementation. A remote attacker
could send a specially-crafted SCTP packet to a target system, resulting in
a denial of service. (CVE-2011-2482, Important)

• A flaw in the Linux kernel's client-side NFS Lock Manager (NLM)

implementation could allow a local, unprivileged user to cause a denial of
service. (CVE-2011-2491, Important)

• Buffer overflow flaws in the Linux kernel's netlink-based wireless

configuration interface implementation could allow a local user, who has
the CAP_NET_ADMIN capability, to cause a denial of service or escalate
their privileges on systems that have an active wireless interface.
(CVE-2011-2517, Important)

• A flaw was found in the way the Linux kernel's Xen hypervisor

implementation emulated the SAHF instruction. When using a
fully-virtualized guest on a host that does not use hardware assisted
paging (HAP), such as those running CPUs that do not have support for (or
those that have it disabled) Intel Extended Page Tables (EPT) or AMD
Virtualization (AMD-V) Rapid Virtualization Indexing (RVI), a privileged
guest user could trigger this flaw to cause the hypervisor to crash.
(CVE-2011-2519, Moderate)

• An off-by-one flaw was found in the __addr_ok() macro in the Linux

kernel's Xen hypervisor implementation when running on 64-bit systems. A
privileged guest user could trigger this flaw to cause the hypervisor to
crash. (CVE-2011-2901, Moderate)

• /proc/[PID]/io is world-readable by default. Previously, these files

could be read without any further restrictions. A local, unprivileged user
could read these files, belonging to other, possibly privileged processes
to gather confidential information, such as the length of a password used
in a process. (CVE-2011-2495, Low)

Red Hat would like to thank Vasily Averin for reporting CVE-2011-2491, and
Vasiliy Kulikov of Openwall for reporting CVE-2011-2495.

This update also fixes several bugs. Documentation for these bug fixes will
be available shortly from the Technical Notes document linked to in the
References section.

Users should upgrade to these updated packages, which contain backported
patches to correct these issues, and fix the bugs noted in the Technical
Notes. 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/kb/docs/DOC-11259

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 Server 5 x86_64
• Red Hat Enterprise Linux Server 5 ia64
• Red Hat Enterprise Linux Server 5 i386
• Red Hat Enterprise Linux Workstation 5 x86_64
• Red Hat Enterprise Linux Workstation 5 i386
• Red Hat Enterprise Linux Desktop 5 x86_64
• Red Hat Enterprise Linux Desktop 5 i386
• Red Hat Enterprise Linux for IBM z Systems 5 s390x
• Red Hat Enterprise Linux for Power, big endian 5 ppc
• Red Hat Enterprise Linux Server from RHUI 5 x86_64
• Red Hat Enterprise Linux Server from RHUI 5 i386

Fixes

• BZ - 709393 - CVE-2011-2491 kernel: rpc task leak after flock()ing NFS share
• BZ - 712885 - RHEL6.1 32bit xen hvm guest crash randomly
• BZ - 714867 - CVE-2011-2482 kernel: sctp dos
• BZ - 716825 - CVE-2011-2495 kernel: /proc/PID/io infoleak
• BZ - 718152 - CVE-2011-2517 kernel: nl80211: missing check for valid SSID size in scan operations
• BZ - 718882 - CVE-2011-2519 kernel: xen: x86_emulate: fix SAHF emulation
• BZ - 727590 - [xfs] mis-sized O_DIRECT I/O results in hung task timeouts [rhel-5.7.z]
• BZ - 727835 - xfs_error_report() oops when passed-in mp is NULL [rhel-5.7.z]
• BZ - 728042 - CVE-2011-2901 kernel: xen: off-by-one shift in x86_64 __addr_ok()

CVEs

• CVE-2011-2517
• CVE-2011-2495
• CVE-2011-2491
• CVE-2011-2519
• CVE-2011-2482
• CVE-2011-2901

References

• https://access.redhat.com/security/updates/classification/#important
• https://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5/html/5.7_Technical_Notes/kernel.html#RHSA-2011-1212