(RHSA-2012:1491) Important: kernel-rt security and bug fix update

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

This update fixes the following security issues:

• A flaw was found in the way Netlink messages without SCM_CREDENTIALS
  (used for authentication) data set were handled. When not explicitly set,
  the data was sent but with all values set to 0, including the process ID
  and user ID, causing the Netlink message to appear as if it were sent with
  root privileges. A local, unprivileged user could use this flaw to send
  spoofed Netlink messages to an application, possibly resulting in the
  application performing privileged operations if it relied on
  SCM_CREDENTIALS data for the authentication of Netlink messages.
  (CVE-2012-3520, Important)

• A race condition was found in the way asynchronous I/O and fallocate()
  interacted when using the ext4 file system. A local, unprivileged user
  could use this flaw to expose random data from an extent whose data blocks
  have not yet been written, and thus contain data from a deleted file.
  (CVE-2012-4508, Important)

• A use-after-free flaw was found in the Linux kernel’s memory management
  subsystem in the way quota handling for huge pages was performed. A local,
  unprivileged user could use this flaw to cause a denial of service or,
  potentially, escalate their privileges. (CVE-2012-2133, Moderate)

• A use-after-free flaw was found in the madvise() system call
  implementation in the Linux kernel. A local, unprivileged user could use
  this flaw to cause a denial of service or, potentially, escalate their
  privileges. (CVE-2012-3511, Moderate)

• A divide-by-zero flaw was found in the TCP Illinois congestion control
  algorithm implementation in the Linux kernel. If the TCP Illinois
  congestion control algorithm were in use (the sysctl
  net.ipv4.tcp_congestion_control variable set to “illinois”), a local,
  unprivileged user could trigger this flaw and cause a denial of service.
  (CVE-2012-4565, Moderate)

• An information leak flaw was found in the uname() system call
  implementation in the Linux kernel. A local, unprivileged user could use
  this flaw to leak kernel stack memory to user-space by setting the UNAME26
  personality and then calling the uname() system call. (CVE-2012-0957, Low)

• Buffer overflow flaws were found in the udf_load_logicalvol() function in
  the Universal Disk Format (UDF) file system implementation in the Linux
  kernel. An attacker with physical access to a system could use these flaws
  to cause a denial of service or escalate their privileges. (CVE-2012-3400,
  Low)

• A flaw was found in the way the msg_namelen variable in the rds_recvmsg()
  function of the Linux kernel’s Reliable Datagram Sockets (RDS) protocol
  implementation was initialized. A local, unprivileged user could use this
  flaw to leak kernel stack memory to user-space. (CVE-2012-3430, Low)

Red Hat would like to thank Pablo Neira Ayuso for reporting CVE-2012-3520;
Theodore Ts’o for reporting CVE-2012-4508; Shachar Raindel for reporting
CVE-2012-2133; and Kees Cook for reporting CVE-2012-0957. Upstream
acknowledges Dmitry Monakhov as the original reporter of CVE-2012-4508. The
CVE-2012-4565 issue was discovered by Rodrigo Freire of Red Hat, and the
CVE-2012-3430 issue was discovered by the Red Hat InfiniBand team.

This update also fixes multiple 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 upgrade the kernel-rt
kernel to version kernel-rt-3.2.33-rt50, and correct these issues. The
system must be rebooted for this update to take effect.