(RHSA-2012:0743) Important: kernel security and bug fix update

The kernel packages contain the Linux kernel, the core of any Linux
operating system.

This update fixes the following security issues:

• A local, unprivileged user could use an integer overflow flaw in
  drm_mode_dirtyfb_ioctl() to cause a denial of service or escalate their
  privileges. (CVE-2012-0044, Important)

• A buffer overflow flaw was found in the macvtap device driver, used for
  creating a bridged network between the guest and the host in KVM
  (Kernel-based Virtual Machine) environments. A privileged guest user in a
  KVM guest could use this flaw to crash the host. Note: This issue only
  affected hosts that have the vhost_net module loaded with the
  experimental_zcopytx module option enabled (it is not enabled by default),
  and that also have macvtap configured for at least one guest.
  (CVE-2012-2119, Important)

• When a set user ID (setuid) application is executed, certain personality
  flags for controlling the application’s behavior are cleared (that is, a
  privileged application will not be affected by those flags). It was found
  that those flags were not cleared if the application was made privileged
  via file system capabilities. A local, unprivileged user could use this
  flaw to change the behavior of such applications, allowing them to bypass
  intended restrictions. Note that for default installations, no application
  shipped by Red Hat for Red Hat Enterprise Linux is made privileged via file
  system capabilities. (CVE-2012-2123, Important)

• 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 privileged guest user in a KVM guest could use this flaw to
  crash the host or, possibly, escalate their privileges on the host.
  (CVE-2012-2136, Important)

• A buffer overflow flaw was found in the setup_routing_entry() function in
  the KVM subsystem of the Linux kernel in the way the Message Signaled
  Interrupts (MSI) routing entry was handled. A local, unprivileged user
  could use this flaw to cause a denial of service or, possibly, escalate
  their privileges. (CVE-2012-2137, Important)

• A race condition was found in the Linux kernel’s memory management
  subsystem in the way pmd_none_or_clear_bad(), when called with mmap_sem in
  read mode, and Transparent Huge Pages (THP) page faults interacted. A
  privileged user in a KVM guest with the ballooning functionality enabled
  could potentially use this flaw to crash the host. A local, unprivileged
  user could use this flaw to crash the system. (CVE-2012-1179, Moderate)

• A flaw was found in the way device memory was handled during guest device
  removal. Upon successful device removal, memory used by the device was not
  properly unmapped from the corresponding IOMMU or properly released from
  the kernel, leading to a memory leak. A malicious user on a KVM host who
  has the ability to assign a device to a guest could use this flaw to crash
  the host. (CVE-2012-2121, Moderate)

• A flaw was found in the Linux kernel’s Reliable Datagram Sockets (RDS)
  protocol implementation. A local, unprivileged user could use this flaw to
  cause a denial of service. (CVE-2012-2372, Moderate)

• A race condition was found in the Linux kernel’s memory management
  subsystem in the way pmd_populate() and pte_offset_map_lock() interacted on
  32-bit x86 systems with more than 4GB of RAM. A local, unprivileged user
  could use this flaw to cause a denial of service. (CVE-2012-2373, Moderate)

Red Hat would like to thank Chen Haogang for reporting CVE-2012-0044.

This update also fixes several bugs. Documentation for these changes will
be available shortly from the Technical Notes document linked to in the
References section.

Users should upgrade to these updated packages, which contain backported
patches to correct these issues, and fix the bugs noted in the Technical
Notes. The system must be rebooted for this update to take effect.