Scientific Linux: CVE-2012-0056 Important Kernel Update and Fix

Date: Wed, 25 Jan 2012 15:18:40 -0600
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Sender: Security Errata for Scientific Linux
 
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Subject: Security ERRATA Important: kernel on SL6.x i386/x86_64
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Synopsis: Important: kernel security and bug fix update
Issue Date: 2012-01-23
CVE Numbers: CVE-2012-0056

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

This update fixes the following security issue:

* It was found that permissions were not checked properly in the Linux
kernel when handling the /proc/[pid]/mem writing functionality. A local,
unprivileged user could use this flaw to escalate their privileges.
(CVE-2012-0056, Important)

This update fixes the following bugs:

* The 2.6.32-220.2.1.el6 kernel update introduced a bug in the Linux kernel
scheduler, causing a "WARNING: at kernel/sched.c:5915 thread_return"
message and a call trace to be logged. This message was harmless, and was
not due to any system malfunctions or adverse behavior. With this update,
the WARN_ON_ONCE() call in the scheduler that caused this harmless message
has been removed.

* The 2.6.32-220.el6 kernel update introduced a regression in the way
the Linux kernel maps ELF headers for kernel modules into kernel memory.
If a third-party kernel module is compiled on a Scientific Linux
system with a kernel prior to 2.6.32-220.el6, then loading that module on
a system with 2.6.32-220.el6 kernel would result in corruption of one byte
in the memory reserved for the module. In some cases, this could prevent
the module from functioning correctly.

* On some SMP systems the tsc may erroneously be marked as unstable during
early system boot or while the system is under heavy load. A "Clocksource
tsc unstable" message was logged when this occurred. As a result the system
would switch to the slower access, but higher precision HPET clock.

The "tsc=reliable" kernel parameter is supposed to avoid this problem by
indicating that the system has a known good clock, however, the parameter
only affected run time checks. A fix has been put in to avoid the boot
time checks so that the TSC remains as the clock for the duration of
system runtime.

Users should upgrade to these updated packages, which contain backported
patches to correct these issues. The system must be rebooted for this
update to take effect.

SL6:
 i386
 kernel-2.6.32-220.4.1.el6.i686.rpm
 kernel-debug-2.6.32-220.4.1.el6.i686.rpm
 kernel-debug-debuginfo-2.6.32-220.4.1.el6.i686.rpm
 kernel-debug-devel-2.6.32-220.4.1.el6.i686.rpm
 kernel-debuginfo-2.6.32-220.4.1.el6.i686.rpm
 kernel-debuginfo-common-i686-2.6.32-220.4.1.el6.i686.rpm
 kernel-devel-2.6.32-220.4.1.el6.i686.rpm
 kernel-headers-2.6.32-220.4.1.el6.i686.rpm
 perf-2.6.32-220.4.1.el6.i686.rpm
 perf-debuginfo-2.6.32-220.4.1.el6.i686.rpm
 python-perf-2.6.32-220.4.1.el6.i686.rpm
 noarch
 kernel-doc-2.6.32-220.4.1.el6.noarch.rpm
 kernel-firmware-2.6.32-220.4.1.el6.noarch.rpm
 x86_64
 kernel-2.6.32-220.4.1.el6.x86_64.rpm
 kernel-debug-2.6.32-220.4.1.el6.x86_64.rpm
 kernel-debug-debuginfo-2.6.32-220.4.1.el6.x86_64.rpm
 kernel-debug-devel-2.6.32-220.4.1.el6.x86_64.rpm
 kernel-debuginfo-2.6.32-220.4.1.el6.x86_64.rpm
 kernel-debuginfo-common-x86_64-2.6.32-220.4.1.el6.x86_64.rpm
 kernel-devel-2.6.32-220.4.1.el6.x86_64.rpm
 kernel-headers-2.6.32-220.4.1.el6.x86_64.rpm
 perf-2.6.32-220.4.1.el6.x86_64.rpm
 perf-debuginfo-2.6.32-220.4.1.el6.x86_64.rpm
 python-perf-2.6.32-220.4.1.el6.x86_64.rpm

- Scientific Linux Development Team