(RHSA-2012:1540) Important: kernel security, bug fix, and enhancement update

These packages contain the Linux kernel.

Security fixes:

• A race condition in the way asynchronous I/O and fallocate() interacted
  when using ext4 could allow a local, unprivileged user to obtain random
  data from a deleted file. (CVE-2012-4508, Important)

• A flaw in the way the Xen hypervisor implementation range checked guest
  provided addresses in the XENMEM_exchange hypercall could allow a
  malicious, para-virtualized guest administrator to crash the hypervisor or,
  potentially, escalate their privileges, allowing them to execute arbitrary
  code at the hypervisor level. (CVE-2012-5513, Important)

• A flaw in the Reliable Datagram Sockets (RDS) protocol implementation
  could allow a local, unprivileged user to cause a denial of service.
  (CVE-2012-2372, Moderate)

• A race condition in the way access to inet->opt ip_options was
  synchronized in the Linux kernel’s TCP/IP protocol suite implementation.
  Depending on the network facing applications running on the system, a
  remote attacker could possibly trigger this flaw to cause a denial of
  service. A local, unprivileged user could use this flaw to cause a denial
  of service regardless of the applications the system runs. (CVE-2012-3552,
  Moderate)

• The Xen hypervisor implementation did not properly restrict the period
  values used to initialize per VCPU periodic timers. A privileged guest user
  could cause an infinite loop on the physical CPU. If the watchdog were
  enabled, it would detect said loop and panic the host system.
  (CVE-2012-4535, Moderate)

• A flaw in the way the Xen hypervisor implementation handled
  set_p2m_entry() error conditions could allow a privileged,
  fully-virtualized guest user to crash the hypervisor. (CVE-2012-4537,
  Moderate)

Red Hat would like to thank Theodore Ts’o for reporting CVE-2012-4508; the
Xen project for reporting CVE-2012-5513, CVE-2012-4535, and CVE-2012-4537;
and Hafid Lin for reporting CVE-2012-3552. Upstream acknowledges Dmitry
Monakhov as the original reporter of CVE-2012-4508. CVE-2012-2372 was
discovered by Li Honggang of Red Hat.

Bug fixes:

• Previously, the interrupt handlers of the qla2xxx driver could clear
  pending interrupts right after the IRQ lines were attached during system
  start-up. Consequently, the kernel could miss the interrupt that reported
  completion of the link initialization, and the qla2xxx driver then failed
  to detect all attached LUNs. With this update, the qla2xxx driver has been
  modified to no longer clear interrupt bits after attaching the IRQ lines.
  The driver now correctly detects all attached LUNs as expected. (BZ#870118)

• The Ethernet channel bonding driver reported the MII (Media Independent
  Interface) status of the bond interface in 802.3ad mode as being up even
  though the MII status of all of the slave devices was down. This could pose
  a problem if the MII status of the bond interface was used to determine if
  failover should occur. With this update, the agg_device_up() function has
  been added to the bonding driver, which allows the driver to report the
  link status of the bond interface correctly, that is, down when all of its
  slaves are down, in the 802.3ad mode. (BZ#877943)

Enhancements:

• This update backports several changes from the latest upstream version of
  the bnx2x driver. The most important change, the remote-fault link
  detection feature, allows the driver to periodically scan the physical link
  layer for remote faults. If the physical link appears to be up and a fault
  is detected, the driver indicates that the link is down. When the fault is
  cleared, the driver indicates that the link is up again. (BZ#870120)

• The INET socket interface has been modified to send a warning message
  when the ip_options structure is allocated directly by a third-party module
  using the kmalloc() function. (BZ#874973)

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