Issued:

2012-07-17

Updated:

2012-07-17

RHSA-2012:1087 - Important: kernel security and bug fix update

Synopsis

Important: kernel security and bug fix update

Type/Severity

Security Advisory Important

Topic

Updated kernel packages that fix one security issue and multiple bugs are now available for Red Hat Enterprise Linux 5.6 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:

• It was found that the data_len parameter of the sock_alloc_send_pskb() function in the Linux kernel's networking implementation was not validated before use. A local user with access to a TUN/TAP virtual interface could use this flaw to crash the system or, potentially, escalate their privileges. Note that unprivileged users cannot access TUN/TAP devices until the root user grants them access. (CVE-2012-2136, Important)

This update also fixes the following bugs:

• An insufficiently designed calculation in the CPU accelerator in the previous kernel caused an arithmetic overflow in the sched_clock() function when system uptime exceeded 208.5 days. This overflow led to a kernel panic on the systems using the Time Stamp Counter (TSC) or Virtual Machine Interface (VMI) clock source. This update corrects the described calculation so that this arithmetic overflow and kernel panic can no longer occur under these circumstances. (BZ#825981, BZ#835449)

• Previously, a race condition between the journal_write_metadata_buffer() and jbd_unlock_bh_state() functions could occur. Consequently, another thread could call the get_write_access() function on the buffer head and cause the wrong data to be written into the journal. If the system terminated unexpectedly or was shut down incorrectly, subsequent file system journal replay could result in file system corruption. This update fixes the race condition and the file system corruption no longer occurs in the described scenario. (BZ#833764)

• When the kvmclock initialization was used in a guest, it could write to the Time Stamp Counter (TSC) and, under certain circumstances, could cause the kernel to become unresponsive on boot. With this update, TSC synchronization, which is unnecessary due to kvmclock, has been disabled, thus fixing this bug. (BZ#834557)

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.

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

Updated Packages

• kernel-debug-2.6.18-238.40.1.el5.x86_64.rpm
• kernel-PAE-2.6.18-238.40.1.el5.i686.rpm
• kernel-kdump-2.6.18-238.40.1.el5.s390x.rpm
• kernel-kdump-devel-2.6.18-238.40.1.el5.ppc64.rpm
• kernel-devel-2.6.18-238.40.1.el5.ppc64.rpm
• kernel-debug-devel-2.6.18-238.40.1.el5.ppc64.rpm
• kernel-xen-2.6.18-238.40.1.el5.i686.rpm
• kernel-debug-debuginfo-2.6.18-238.40.1.el5.i686.rpm
• kernel-PAE-devel-2.6.18-238.40.1.el5.i686.rpm
• kernel-headers-2.6.18-238.40.1.el5.s390x.rpm
• kernel-devel-2.6.18-238.40.1.el5.s390x.rpm
• kernel-2.6.18-238.40.1.el5.x86_64.rpm
• kernel-debuginfo-common-2.6.18-238.40.1.el5.x86_64.rpm
• kernel-xen-2.6.18-238.40.1.el5.ia64.rpm
• kernel-headers-2.6.18-238.40.1.el5.ppc64.rpm
• kernel-doc-2.6.18-238.40.1.el5.noarch.rpm
• kernel-2.6.18-238.40.1.el5.ia64.rpm
• kernel-headers-2.6.18-238.40.1.el5.ppc.rpm
• kernel-debug-2.6.18-238.40.1.el5.ia64.rpm
• kernel-debug-devel-2.6.18-238.40.1.el5.ia64.rpm
• kernel-2.6.18-238.40.1.el5.src.rpm
• kernel-debug-debuginfo-2.6.18-238.40.1.el5.x86_64.rpm
• kernel-debuginfo-2.6.18-238.40.1.el5.x86_64.rpm
• kernel-devel-2.6.18-238.40.1.el5.ia64.rpm
• kernel-xen-2.6.18-238.40.1.el5.x86_64.rpm
• kernel-kdump-devel-2.6.18-238.40.1.el5.s390x.rpm
• kernel-devel-2.6.18-238.40.1.el5.i686.rpm
• kernel-xen-devel-2.6.18-238.40.1.el5.i686.rpm
• kernel-debug-debuginfo-2.6.18-238.40.1.el5.ia64.rpm
• kernel-headers-2.6.18-238.40.1.el5.ia64.rpm
• kernel-debug-2.6.18-238.40.1.el5.s390x.rpm
• kernel-debuginfo-2.6.18-238.40.1.el5.i686.rpm
• kernel-kdump-2.6.18-238.40.1.el5.ppc64.rpm
• kernel-xen-debuginfo-2.6.18-238.40.1.el5.i686.rpm
• kernel-debuginfo-common-2.6.18-238.40.1.el5.i686.rpm
• kernel-debug-devel-2.6.18-238.40.1.el5.s390x.rpm
• kernel-2.6.18-238.40.1.el5.s390x.rpm
• kernel-2.6.18-238.40.1.el5.ppc64.rpm
• kernel-headers-2.6.18-238.40.1.el5.x86_64.rpm
• kernel-xen-devel-2.6.18-238.40.1.el5.ia64.rpm
• kernel-devel-2.6.18-238.40.1.el5.x86_64.rpm
• kernel-debug-2.6.18-238.40.1.el5.ppc64.rpm
• kernel-PAE-debuginfo-2.6.18-238.40.1.el5.i686.rpm
• kernel-debuginfo-common-2.6.18-238.40.1.el5.ia64.rpm
• kernel-debug-2.6.18-238.40.1.el5.i686.rpm
• kernel-2.6.18-238.40.1.el5.i686.rpm
• kernel-debug-devel-2.6.18-238.40.1.el5.x86_64.rpm
• kernel-xen-debuginfo-2.6.18-238.40.1.el5.x86_64.rpm
• kernel-xen-devel-2.6.18-238.40.1.el5.x86_64.rpm
• kernel-debuginfo-2.6.18-238.40.1.el5.ia64.rpm
• kernel-debug-devel-2.6.18-238.40.1.el5.i686.rpm
• kernel-xen-debuginfo-2.6.18-238.40.1.el5.ia64.rpm
• kernel-headers-2.6.18-238.40.1.el5.i386.rpm

Fixes

• This content is not included.BZ - 816289

CVEs

• CVE-2012-2136

References

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

Additional information

• The Red Hat security contact is This content is not included.secalert@redhat.com. More contact details at https://access.redhat.com/security/team/contact/.
• Offline Security Data data is available for integration with other systems. See Offline Security Data API to get started.