kernel (SL7)

Synopsis: Important: kernel security and bug fix update
Advisory ID: SLSA-2016:1033-1
Issue Date: 2016-05-12
CVE Numbers: CVE-2016-0758

Security Fix(es):

* A flaw was found in the way the Linux kernel’s ASN.1 DER decoder
processed certain certificate files with tags of indefinite length. A
local, unprivileged user could use a specially crafted X.509 certificate
DER file to crash the system or, potentially, escalate their privileges on
the system. (CVE-2016-0758, Important)

Bug Fix(es):

* Under certain conditions, the migration threads could race with the CPU
hotplug, which could cause a deadlock. A set of patches has been provided
to fix this bug, and the deadlock no longer occurs in the system.

* A bug in the code that cleans up revoked delegations could previously
cause a soft lockup in the NFS server. This patch fixes the underlying
source code, so the lockup no longer occurs.

* The second attempt to reload Common Application Programming Interface
(CAPI) devices on the little-endian variant of IBM Power Systems
previously failed. The provided set of patches fixes this bug, and
reloading works as intended.

* Due to inconsistencies in page size of IOMMU, the NVMe device, and the
kernel, the BUG_ON signal previously occurred in the nvme_setup_prps()
function, leading to the system crash while setting up the DMA transfer.
The provided patch sets the default NVMe page size to 4k, thus preventing
the system crash.

* Previously, on a system using the Infiniband mlx5 driver used for the
SRP stack, a hard lockup previously occurred after the kernel exceeded
time with lock held with interrupts blocked. As a consequence, the system
panicked. This update fixes this bug, and the system no longer panics in
this situation.

* On the little-endian variant of IBM Power Systems, the kernel previously
crashed in the bitmap_weight() function while running the memory affinity
script. The provided patch fortifies the topology setup and prevents
sd->child from being set to NULL when it is already NULL. As a result, the
memory affinity script runs successfully.

* When a KVM guest wrote random values to the special-purpose registers
(SPR) Instruction Authority Mask Register (IAMR), the guest and the
corresponding QEMU process previously hung. This update adds the code
which sets SPRs to a suitable neutral value on guest exit, thus fixing
this bug.

* Under heavy iSCSI traffic load, the system previously panicked due to a
race in the locking code leading to a list corruption. This update fixes
this bug, and the system no longer panics in this situation.

* During SCSI exception handling (triggered by some irregularities), the
driver could previously use an already retired SCSI command. As a
consequence, a kernel panic or data corruption occurred. The provided
patches fix this bug, and exception handling now proceeds successfully.

* When the previously opened /dev/tty, which pointed to a pseudo terminal
(pty) pair, was the last file closed, a kernel crash could previously
occur. The underlying source code has been fixed, preventing this bug.

* Previously, when using VPLEX and FCoE via the bnx2fc driver, different
degrees of data corruption occurred. The provided patch fixes the FCP
Response (RSP) residual parsing in bnx2fc, which prevents the
aforementioned corruption.


– Scientific Linux Development Team