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[RHSA-2012:1491-01] Important: kernel-rt security and bug fix update

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Red Hat Security Advisory


Synopsis: Important: kernel-rt security and bug fix update

Advisory ID: RHSA-2012:1491-01

Product: Red Hat Enterprise MRG for RHEL-6

Advisory URL: https://rhn.redhat.com/errata/RHSA-2012-1491.html

Issue date: 2012-12-04

CVE Names: CVE-2012-0957 CVE-2012-2133 CVE-2012-3400

CVE-2012-3430 CVE-2012-3511 CVE-2012-3520

CVE-2012-4508 CVE-2012-4565



1. Summary:


Updated kernel-rt packages that fix several security issues and multiple

bugs are now available for Red Hat Enterprise MRG 2.2.


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.


2. Relevant releases/architectures:


MRG Realtime for RHEL 6 Server v.2 - noarch, x86_64


3. Description:


The kernel-rt packages contain the Linux kernel, the core of any Linux

operating system.


This update fixes the following security issues:


* A flaw was found in the way Netlink messages without SCM_CREDENTIALS

(used for authentication) data set were handled. When not explicitly set,

the data was sent but with all values set to 0, including the process ID

and user ID, causing the Netlink message to appear as if it were sent with

root privileges. A local, unprivileged user could use this flaw to send

spoofed Netlink messages to an application, possibly resulting in the

application performing privileged operations if it relied on

SCM_CREDENTIALS data for the authentication of Netlink messages.

(CVE-2012-3520, Important)


* A race condition was found in the way asynchronous I/O and fallocate()

interacted when using the ext4 file system. A local, unprivileged user

could use this flaw to expose random data from an extent whose data blocks

have not yet been written, and thus contain data from a deleted file.

(CVE-2012-4508, Important)


* A use-after-free flaw was found in the Linux kernel's memory management

subsystem in the way quota handling for huge pages was performed. A local,

unprivileged user could use this flaw to cause a denial of service or,

potentially, escalate their privileges. (CVE-2012-2133, Moderate)


* A use-after-free flaw was found in the madvise() system call

implementation in the Linux kernel. A local, unprivileged user could use

this flaw to cause a denial of service or, potentially, escalate their

privileges. (CVE-2012-3511, Moderate)


* A divide-by-zero flaw was found in the TCP Illinois congestion control

algorithm implementation in the Linux kernel. If the TCP Illinois

congestion control algorithm were in use (the sysctl

net.ipv4.tcp_congestion_control variable set to "illinois"), a local,

unprivileged user could trigger this flaw and cause a denial of service.

(CVE-2012-4565, Moderate)


* An information leak flaw was found in the uname() system call

implementation in the Linux kernel. A local, unprivileged user could use

this flaw to leak kernel stack memory to user-space by setting the UNAME26

personality and then calling the uname() system call. (CVE-2012-0957, Low)


* Buffer overflow flaws were found in the udf_load_logicalvol() function in

the Universal Disk Format (UDF) file system implementation in the Linux

kernel. An attacker with physical access to a system could use these flaws

to cause a denial of service or escalate their privileges. (CVE-2012-3400,



* A flaw was found in the way the msg_namelen variable in the rds_recvmsg()

function of the Linux kernel's Reliable Datagram Sockets (RDS) protocol

implementation was initialized. A local, unprivileged user could use this

flaw to leak kernel stack memory to user-space. (CVE-2012-3430, Low)


Red Hat would like to thank Pablo Neira Ayuso for reporting CVE-2012-3520;

Theodore Ts'o for reporting CVE-2012-4508; Shachar Raindel for reporting

CVE-2012-2133; and Kees Cook for reporting CVE-2012-0957. Upstream

acknowledges Dmitry Monakhov as the original reporter of CVE-2012-4508. The

CVE-2012-4565 issue was discovered by Rodrigo Freire of Red Hat, and the

CVE-2012-3430 issue was discovered by the Red Hat InfiniBand team.


This update also fixes multiple bugs. Documentation for these changes will

be available shortly from the Technical Notes document linked to in the

References section.


Users should upgrade to these updated packages, which upgrade the kernel-rt

kernel to version kernel-rt-3.2.33-rt50, and correct these issues. The

system must be rebooted for this update to take effect.


4. 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



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.


5. Bugs fixed (http://bugzilla.redhat.com/):


817430 - CVE-2012-2133 kernel: use after free bug in "quota" handling

820039 - CVE-2012-3430 kernel: recv{from,msg}() on an rds socket can leak kernel memory

843130 - RFE kernel: net: mitigate blind reset attacks using RST and SYN bits

843139 - CVE-2012-3400 kernel: udf: buffer overflow when parsing sparing table

849734 - CVE-2012-3511 kernel: mm: use-after-free in madvise_remove()

850449 - CVE-2012-3520 kernel: af_netlink: invalid handling of SCM_CREDENTIALS passing

856243 - kernel-rt-debug potential deadlock

859226 - iptables and other tools unable to log to rsyslog

862877 - CVE-2012-0957 kernel: uts: stack memory leak in UNAME26

864568 - Rebase MRG Realtime kernel to latest upstream 3.2 stable RT release

869904 - CVE-2012-4508 kernel: ext4: AIO vs fallocate stale data exposure

871848 - CVE-2012-4565 kernel: net: divide by zero in tcp algorithm illinois


6. Package List:


MRG Realtime for RHEL 6 Server v.2:

























These packages are GPG signed by Red Hat for security. Our key and

details on how to verify the signature are available from



7. References:













8. Contact:


The Red Hat security contact is . More contact

details at https://access.redhat.com/security/team/contact/


Copyright 2012 Red Hat, Inc.


Version: GnuPG v1.4.4 (GNU/Linux)










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