(RHSA-2015:2152) Important: kernel security, bug fix, and enhancement update

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

• A flaw was found in the way the Linux kernel’s file system implementation
  handled rename operations in which the source was inside and the
  destination was outside of a bind mount. A privileged user inside a
  container could use this flaw to escape the bind mount and, potentially,
  escalate their privileges on the system. (CVE-2015-2925, Important)

• A race condition flaw was found in the way the Linux kernel’s IPC
  subsystem initialized certain fields in an IPC object structure that were
  later used for permission checking before inserting the object into a
  globally visible list. A local, unprivileged user could potentially use
  this flaw to elevate their privileges on the system. (CVE-2015-7613,
  Important)

• It was found that reporting emulation failures to user space could lead
  to either a local (CVE-2014-7842) or a L2->L1 (CVE-2010-5313) denial of
  service. In the case of a local denial of service, an attacker must have
  access to the MMIO area or be able to access an I/O port. (CVE-2010-5313,
  CVE-2014-7842, Moderate)

• A flaw was found in the way the Linux kernel’s KVM subsystem handled
  non-canonical addresses when emulating instructions that change the RIP
  (for example, branches or calls). A guest user with access to an I/O or
  MMIO region could use this flaw to crash the guest. (CVE-2014-3647,
  Moderate)

• It was found that the Linux kernel memory resource controller’s (memcg)
  handling of OOM (out of memory) conditions could lead to deadlocks.
  An attacker could use this flaw to lock up the system. (CVE-2014-8171,
  Moderate)

• A race condition flaw was found between the chown and execve system
  calls. A local, unprivileged user could potentially use this flaw to
  escalate their privileges on the system. (CVE-2015-3339, Moderate)

• A flaw was discovered in the way the Linux kernel’s TTY subsystem handled
  the tty shutdown phase. A local, unprivileged user could use this flaw to
  cause a denial of service on the system. (CVE-2015-4170, Moderate)

• A NULL pointer dereference flaw was found in the SCTP implementation.
  A local user could use this flaw to cause a denial of service on the system
  by triggering a kernel panic when creating multiple sockets in parallel
  while the system did not have the SCTP module loaded. (CVE-2015-5283,
  Moderate)

• A flaw was found in the way the Linux kernel’s perf subsystem retrieved
  userlevel stack traces on PowerPC systems. A local, unprivileged user could
  use this flaw to cause a denial of service on the system. (CVE-2015-6526,
  Moderate)

• A flaw was found in the way the Linux kernel’s Crypto subsystem handled
  automatic loading of kernel modules. A local user could use this flaw to
  load any installed kernel module, and thus increase the attack surface of
  the running kernel. (CVE-2013-7421, CVE-2014-9644, Low)

• An information leak flaw was found in the way the Linux kernel changed
  certain segment registers and thread-local storage (TLS) during a context
  switch. A local, unprivileged user could use this flaw to leak the user
  space TLS base address of an arbitrary process. (CVE-2014-9419, Low)

• It was found that the Linux kernel KVM subsystem’s sysenter instruction
  emulation was not sufficient. An unprivileged guest user could use this
  flaw to escalate their privileges by tricking the hypervisor to emulate a
  SYSENTER instruction in 16-bit mode, if the guest OS did not initialize the
  SYSENTER model-specific registers (MSRs). Note: Certified guest operating
  systems for Red Hat Enterprise Linux with KVM do initialize the SYSENTER
  MSRs and are thus not vulnerable to this issue when running on a KVM
  hypervisor. (CVE-2015-0239, Low)

• A flaw was found in the way the Linux kernel handled the securelevel
  functionality after performing a kexec operation. A local attacker could
  use this flaw to bypass the security mechanism of the
  securelevel/secureboot combination. (CVE-2015-7837, Low)