(RHSA-2012:1042) 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)

• It was found that the kvm_vm_ioctl_assign_device() function in the KVM
  (Kernel-based Virtual Machine) subsystem of a Linux kernel did not check if
  the user requesting device assignment was privileged or not. A local,
  unprivileged user on the host could assign unused PCI devices, or even
  devices that were in use and whose resources were not properly claimed by
  the respective drivers, which could result in the host crashing.
  (CVE-2011-4347, Moderate)

• A flaw was found in the way the Linux kernel’s XFS file system
  implementation handled on-disk Access Control Lists (ACLs). A local,
  unprivileged user could use this flaw to cause a denial of service or
  escalate their privileges by mounting a specially-crafted disk.
  (CVE-2012-0038, Moderate)

• It was found that the Linux kernel’s register set (regset) common
  infrastructure implementation did not check if the required get and set
  handlers were initialized. A local, unprivileged user could use this flaw
  to cause a denial of service by performing a register set operation with a
  ptrace() PTRACE_SETREGSET or PTRACE_GETREGSET request. (CVE-2012-1097,
  Moderate)

• 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)

Red Hat would like to thank Chen Haogang for reporting CVE-2012-0044; Sasha
Levin for reporting CVE-2011-4347; Wang Xi for reporting CVE-2012-0038; and
H. Peter Anvin for reporting CVE-2012-1097.

This update also fixes the following bugs:

• When a RoCE (RDMA over Converged Ethernet) adapter with active RoCE
  communications was taken down suddenly (either by adapter failure or the
  intentional shutdown of the interface), the ongoing RoCE communications
  could cause the kernel to panic and render the machine unusable. A patch
  has been provided to protect the kernel in this situation and to pass an
  error up to the application still using the interface after it has been
  taken down instead. (BZ#799944)

• The fix for Red Hat Bugzilla bug 713494, released via RHSA-2011:0928,
  introduced a regression. Attempting to change the state of certain
  features, such as GRO (Generic Receive Offload) or TSO (TCP segment
  offloading), for a 10 Gigabit Ethernet card that is being used in a
  virtual LAN (VLAN) resulted in a kernel panic. (BZ#816974)

• If a new file was created on a Network File System version 4 (NFSv4)
  share, the ownership was set to nfsnobody (-2) until it was possible to
  upcall to the idmapper. As a consequence, subsequent file system operations
  could incorrectly use “-2” for the user and group IDs for the given file,
  causing certain operations to fail. In reported cases, this issue also
  caused “Viminfo file is not writable” errors for users running Vim with
  files on an NFSv4 share. (BZ#820960)

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.