kernel (SL7)

Synopsis: Important: kernel security and bug fix update
Advisory ID: SLSA-2015:0726-1
Issue Date: 2015-03-26
CVE Numbers: CVE-2014-8159

* It was found that the Linux kernel’s Infiniband subsystem did not
properly sanitize input parameters while registering memory regions from
user space via the (u)verbs API. A local user with access to a
/dev/infiniband/uverbsX device could use this flaw to crash the system or,
potentially, escalate their privileges on the system. (CVE-2014-8159,

* A use-after-free flaw was found in the way the Linux kernel’s SCTP
implementation handled authentication key reference counting during INIT
collisions. A remote attacker could use this flaw to crash the system or,
potentially, escalate their privileges on the system. (CVE-2015-1421,

This update also fixes the following bugs:

* In certain systems with multiple CPUs, when a crash was triggered on one
CPU with an interrupt handler and this CPU sent Non-Maskable Interrupt
(NMI) to another CPU, and, at the same time, ioapic_lock had already been
acquired, a deadlock occurred in ioapic_lock. As a consequence, the kdump
service could become unresponsive. This bug has been fixed and kdump now
works as expected.

* On Lenovo X1 Carbon 3rd Gen, X250, and T550 laptops, the thinkpad_acpi
module was not properly loaded, and thus the function keys and radio
switches did not work. This update applies a new string pattern of BIOS
version, which fixes this bug, and function keys and radio switches now
work as intended.

* During a heavy file system load involving many worker threads, all
worker threads in the pool became blocked on a resource, and no manager
thread existed to create more workers. As a consequence, the running
processes became unresponsive. With this update, the logic around manager
creation has been changed to assure that the last worker thread becomes a
manager thread and does not start executing work items. Now, a manager
thread exists, spawns new workers as needed, and processes no longer hang.

* If a thin-pool’s metadata enters read-only or fail mode, for example,
due to thin-pool running out of metadata or data space, any attempt to
make metadata changes such as creating a thin device or snapshot thin
device should error out cleanly. However, previously, the kernel code
returned verbose and alarming error messages to the user. With this
update, due to early trapping of attempt to make metadata changes,
informative errors are displayed, no longer unnecessarily alarming the

* When running Scientific Linux as a guest on Microsoft Hyper-V
hypervisor, the storvsc module did not return the correct error code for
the upper level Small Computer System Interface (SCSI) subsystem. As a
consequence, a SCSI command failed and storvsc did not handle such a
failure properly under some conditions, for example, when RAID devices
were created on top of storvsc devices. An upstream patch has been applied
to fix this bug, and storvsc now returns the correct error code in the
described situation.

The system must be rebooted for this update to take effect.


– Scientific Linux Development Team