6.5 - RHSA-2013:0882

Problem Description:

Updated kernel packages that fix multiple security issues and several bugs are now available for Red Hat Enterprise Linux 6.2 Extended Update Support.

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:

Red Hat Enterprise Linux Server EUS (v. 6.2) - i386, noarch, ppc64, s390x, x86_64 Red Hat Enterprise Linux Server Optional EUS (v. 6.2) - i386, ppc64, s390x, x86_64

3. Description:

The kernel 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 the vhost kernel module handled descriptors that spanned multiple regions. A privileged guest user in a KVM (Kernel-based Virtual Machine) guest could use this flaw to crash the host or, potentially, escalate their privileges on the host. (CVE-2013-0311, Important)

* A flaw was found in the way the KVM subsystem handled guests attempting to run with the X86_CR4_OSXSAVE CPU feature flag set. On hosts without the XSAVE CPU feature, a local, unprivileged user could use this flaw to crash the host system. (The "grep --color xsave /proc/cpuinfo" command can be used to verify if your system has the XSAVE CPU feature.) (CVE-2012-4461, Moderate)

* It was found that the default SCSI command filter does not accommodate commands that overlap across device classes. A privileged guest user could potentially use this flaw to write arbitrary data to a LUN that is passed-through as read-only. (CVE-2012-4542, Moderate)

* A use-after-free flaw was found in the tmpfs implementation. A local user able to mount and unmount a tmpfs file system could use this flaw to cause a denial of service or, potentially, escalate their privileges. (CVE-2013-1767, Low)

Red Hat would like to thank Jon Howell for reporting CVE-2012-4461. CVE-2012-4542 was discovered by Paolo Bonzini of Red Hat.

This update also fixes the following bugs:

* Previously, when open(2) system calls were processed, the GETATTR routine did not check to see if valid attributes were also returned. As a result, the open() call succeeded with invalid attributes instead of failing in such a case. This update adds the missing check, and the open() call succeeds only when valid attributes are returned. (BZ#960409)

* Previously, the fsync(2) system call incorrectly returned the EIO (Input/Output) error instead of the ENOSPC (No space left on device) error. This was due to incorrect error handling in the page cache. This problem has been fixed and the correct error value is now returned. (BZ#960418)

* In the RPC code, when a network socket backed up due to high network traffic, a timer was set causing a retransmission, which in turn could cause an even larger amount of network traffic to be generated. To prevent this problem, the RPC code now waits for the socket to empty instead of setting the timer. (BZ#960423)

* This update fixes a number of bugs in the be2iscsi driver for ServerEngines BladeEngine 2 Open iSCSI devices. (BZ#955502)

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.

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 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.

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

862900 - CVE-2012-4461 kernel: kvm: invalid opcode oops on SET_SREGS with OSXSAVE bit set 875360 - CVE-2012-4542 kernel: block: default SCSI command filter does not accomodate commands overlap across device classes 912905 - CVE-2013-0311 kernel: vhost: fix length for cross region descriptor 915592 - CVE-2013-1767 Kernel: tmpfs: fix use-after-free of mempolicy object