7.8 - RHSA-2012:0107

Problem Description:

Updated kernel packages that fix multiple security issues and two 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.

2. Relevant releases/architectures:

Red Hat Enterprise Linux (v. 5 server) - i386, ia64, noarch, ppc, s390x, x86_64 Red Hat Enterprise Linux Desktop (v. 5 client) - i386, noarch, 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:

* Using the SG_IO ioctl to issue SCSI requests to partitions or LVM volumes resulted in the requests being passed to the underlying block device. If a privileged user only had access to a single partition or LVM volume, they could use this flaw to bypass those restrictions and gain read and write access (and be able to issue other SCSI commands) to the entire block device. Refer to Red Hat Knowledgebase article DOC-67874, linked to in the References, for further details about this issue. (CVE-2011-4127, Important)

* A flaw was found in the way the Linux kernel handled robust list pointers of user-space held futexes across exec() calls. A local, unprivileged user could use this flaw to cause a denial of service or, eventually, escalate their privileges. (CVE-2012-0028, Important)

* A flaw was found in the Linux kernel in the way splitting two extents in ext4_ext_convert_to_initialized() worked. A local, unprivileged user with the ability to mount and unmount ext4 file systems could use this flaw to cause a denial of service. (CVE-2011-3638, Moderate)

* A flaw was found in the way the Linux kernel's journal_unmap_buffer() function handled buffer head states. On systems that have an ext4 file system with a journal mounted, a local, unprivileged user could use this flaw to cause a denial of service. (CVE-2011-4086, Moderate)

* A divide-by-zero flaw was found in the Linux kernel's igmp_heard_query() function. An attacker able to send certain IGMP (Internet Group Management Protocol) packets to a target system could use this flaw to cause a denial of service. (CVE-2012-0207, Moderate)

Red Hat would like to thank Zheng Liu for reporting CVE-2011-3638, and Simon McVittie for reporting CVE-2012-0207.

This update also fixes the following bugs:

* When a host was in recovery mode and a SCSI scan operation was initiated, the scan operation failed and provided no error output. This bug has been fixed and the SCSI layer now waits for recovery of the host to complete scan operations for devices. (BZ#772162)

* SG_IO ioctls were not implemented correctly in the Red Hat Enterprise Linux 5 virtio-blk driver. Sending an SG_IO ioctl request to a virtio-blk disk caused the sending thread to enter an uninterruptible sleep state ("D" state). With this update, SG_IO ioctls are rejected by the virtio-blk driver: the ioctl system call will simply return an ENOTTY ("Inappropriate ioctl for device") error and the thread will continue normally. (BZ#773322)

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/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.

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

747942 - CVE-2011-3638 kernel: ext4: ext4_ext_insert_extent() kernel oops 749143 - CVE-2011-4086 kernel: jbd2: unmapped buffer with _Unwritten or _Delay flags set can lead to DoS 752375 - CVE-2011-4127 kernel: possible privilege escalation via SG_IO ioctl 771764 - CVE-2012-0028 kernel: futex: clear robust_list on execve 772867 - CVE-2012-0207 kernel: igmp: Avoid zero delay when receiving odd mixture of IGMP queries