| 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.
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