[RHSA-2011:0883] kernel security and bug fix update

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

This update includes backported fixes for security issues. These issues,
except for CVE-2011-1182, only affected users of Red Hat Enterprise Linux
6.0 Extended Update Support as they have already been addressed for users
of Red Hat Enterprise Linux 6 in the 6.1 update, RHSA-2011:0542.

Security fixes:

• Buffer overflow flaws were found in the Linux kernel's Management Module
  Support for Message Passing Technology (MPT) based controllers. A local,
  unprivileged user could use these flaws to cause a denial of service, an
  information leak, or escalate their privileges. (CVE-2011-1494,
  CVE-2011-1495, Important)

• A flaw was found in the Linux kernel's networking subsystem. If the
  number of packets received exceeded the receiver's buffer limit, they were
  queued in a backlog, consuming memory, instead of being discarded. A remote
  attacker could abuse this flaw to cause a denial of service (out-of-memory
  condition). (CVE-2010-4251, CVE-2010-4805, Moderate)

• A flaw was found in the Linux kernel's Transparent Huge Pages (THP)
  implementation. A local, unprivileged user could abuse this flaw to allow
  the user stack (when it is using huge pages) to grow and cause a denial of
  service. (CVE-2011-0999, Moderate)

• A flaw in the Linux kernel's Event Poll (epoll) implementation could
  allow a local, unprivileged user to cause a denial of service.
  (CVE-2011-1082, Moderate)

• An inconsistency was found in the interaction between the Linux kernel's
  method for allocating NFSv4 (Network File System version 4) ACL data and
  the method by which it was freed. This inconsistency led to a kernel panic
  which could be triggered by a local, unprivileged user with files owned by
  said user on an NFSv4 share. (CVE-2011-1090, Moderate)

• It was found that some structure padding and reserved fields in certain
  data structures in KVM (Kernel-based Virtual Machine) were not initialized
  properly before being copied to user-space. A privileged host user with
  access to "/dev/kvm" could use this flaw to leak kernel stack memory to
  user-space. (CVE-2010-3881, Low)

• A missing validation check was found in the Linux kernel's
  mac_partition() implementation, used for supporting file systems created on
  Mac OS operating systems. A local attacker could use this flaw to cause a
  denial of service by mounting a disk that contains specially-crafted
  partitions. (CVE-2011-1010, Low)

• A buffer overflow flaw in the DEC Alpha OSF partition implementation in
  the Linux kernel could allow a local attacker to cause an information leak
  by mounting a disk that contains specially-crafted partition tables.
  (CVE-2011-1163, Low)

• Missing validations of null-terminated string data structure elements in
  the do_replace(), compat_do_replace(), do_ipt_get_ctl(), do_ip6t_get_ctl(),
  and do_arpt_get_ctl() functions could allow a local user who has the
  CAP_NET_ADMIN capability to cause an information leak. (CVE-2011-1170,
  CVE-2011-1171, CVE-2011-1172, Low)

• A missing validation check was found in the Linux kernel's signals
  implementation. A local, unprivileged user could use this flaw to send
  signals via the sigqueueinfo system call, with the si_code set to SI_TKILL
  and with spoofed process and user IDs, to other processes. Note: This flaw
  does not allow existing permission checks to be bypassed; signals can only
  be sent if your privileges allow you to already do so. (CVE-2011-1182, Low)

Red Hat would like to thank Dan Rosenberg for reporting CVE-2011-1494 and
CVE-2011-1495; Nelson Elhage for reporting CVE-2011-1082; Vasiliy
Kulikov for reporting CVE-2010-3881, CVE-2011-1170, CVE-2011-1171, and
CVE-2011-1172; Timo Warns for reporting CVE-2011-1010 and CVE-2011-1163;
and Julien Tinnes of the Google Security Team for reporting CVE-2011-1182.

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