Synopsis: Important: kernel security and bug fix update
Advisory ID: SLSA-2017:0036-1
Issue Date: 2017-01-10
CVE Numbers: CVE-2016-4998
* A use-after-free vulnerability was found in the kernels socket recvmmsg
subsystem. This may allow remote attackers to corrupt memory and may allow
execution of arbitrary code. This corruption takes place during the error
handling routines within __sys_recvmmsg() function. (CVE-2016-7117,
* An out-of-bounds heap memory access leading to a Denial of Service, heap
disclosure, or further impact was found in setsockopt(). The function call
is normally restricted to root, however some processes with cap_sys_admin
may also be able to trigger this flaw in privileged container
environments. (CVE-2016-4998, Moderate)
* A use-after-free vulnerability was found in tcp_xmit_retransmit_queue
and other tcp_* functions. This condition could allow an attacker to send
an incorrect selective acknowledgment to existing connections, possibly
resetting a connection. (CVE-2016-6828, Moderate)
* When parallel NFS returned a file layout, a kernel crash sometimes
occurred. This update removes the call to the BUG_ON() function from a
code path of a client that returns the file layout. As a result, the
kernel no longer crashes in the described situation.
* When a guest virtual machine (VM) on Microsoft Hyper-V was set to crash
on a Nonmaskable Interrupt (NMI) that was injected from the host, this VM
became unresponsive and did not create the vmcore dump file. This update
applies a set of patches to the Virtual Machine Bus kernel driver
(hv_vmbus) that fix this bug. As a result, the VM now first creates and
saves the vmcore dump file and then reboots.
* From Scientific Linux 6.6 to 6.8, the IPv6 routing cache occasionally
showed incorrect values. This update fixes the DST_NOCOUNT mechanism, and
the IPv6 routing cache now shows correct values.
* When using the ixgbe driver and the software Fibre Channel over Ethernet
(FCoE) stack, suboptimal performance in some cases occurred on systems
with a large number of CPUs. This update fixes the fc_exch_alloc()
function to try all the available exchange managers in the list for an
available exchange ID. This change avoids failing allocations, which
previously led to the host busy status.
* When the vmwgfx kernel module loads, it overrides the boot resolution
automatically. Consequently, users were not able to change the resolution
by manual setting of the kernel's 'vga=' parameter in the
/boot/grub/grub.conf file. This update adds the 'nomodeset' parameter,
which can be set in the /boot/grub/grub.conf file. The 'nomodeset'
parameter allows the users to prevent the vmwgfx driver from loading. As a
result, the setting of the 'vga=' parameter works as expected, in case
that vmwgfx does not load.
* When Scientific Linux 6.8 was booted on SMBIOS 3.0 based systems,
Desktop Management Interface (DMI) information, which is referenced by
several applications, such as NEC server's memory RAS utility, was missing
entries in the sysfs virtual file system. This update fixes the underlying
source code, and sysfs now shows the DMI information as expected.
* Previously, bonding mode active backup and the propagation of the media
access control (MAC) address to a VLAN interface did not work in
Scientific Linux 6.8, when the fail_over_mac bonding parameter was set to
fail_over_mac=active. With this update, the underlying source code has
been fixed so that the VLANs continue inheriting the MAC address of the
active physical interface until the VLAN MAC address is explicitly set to
any value. As a result, IPv6 EUI64 addresses for the VLAN can reflect any
changes to the MAC address of the physical interface, and Duplicate
Address Detection (DAD) behaves as expected.
- Scientific Linux Development Team