Scientific Linux Security Update : kernel on SL6.x i386/x86_64

Critical Nessus Plugin ID 106369


The remote Scientific Linux host is missing one or more security updates.


Security Fix(es) :

- An integer overflow vulnerability in ip6_find_1stfragopt() function was found. A local attacker that has privileges (of CAP_NET_RAW) to open raw socket can cause an infinite loop inside the ip6_find_1stfragopt() function. (CVE-2017-7542, Moderate)

- The IPv6 fragmentation implementation in the Linux kernel does not consider that the nexthdr field may be associated with an invalid option, which allows local users to cause a denial of service (out-of-bounds read and BUG) or possibly have unspecified other impact via crafted socket and send system calls. Due to the nature of the flaw, privilege escalation cannot be fully ruled out, although we believe it is unlikely. (CVE-2017-9074, Moderate)

- A use-after-free flaw was found in the Netlink functionality of the Linux kernel networking subsystem.
Due to the insufficient cleanup in the mq_notify function, a local attacker could potentially use this flaw to escalate their privileges on the system.
(CVE-2017-11176, Moderate)

Bug Fix(es) :

- Previously, the default timeout and retry settings in the VMBus driver were insufficient in some cases, for example when a Hyper-V host was under a significant load. Consequently, in Windows Server 2016, Hyper-V Server 2016, and Windows Azure Platform, when running a Scientific Linux Guest on the Hyper-V hypervisor, the guest failed to boot or booted with certain Hyper-V devices missing. This update alters the timeout and retry settings in VMBus, and Scientific Linux guests now boot as expected under the described conditions.

- Previously, an incorrect external declaration in the be2iscsi driver caused a kernel panic when using the systool utility. With this update, the external declaration in be2iscsi has been fixed, and the kernel no longer panics when using systool.

- Under high usage of the NFSD file system and memory pressure, if many tasks in the Linux kernel attempted to obtain the global spinlock to clean the Duplicate Reply Cache (DRC), these tasks stayed in an active wait in the nfsd_reply_cache_shrink() function for up to 99% of time. Consequently, a high load average occurred. This update fixes the bug by separating the DRC in several parts, each with an independent spinlock. As a result, the load and CPU utilization is no longer excessive under the described circumstances.

- When attempting to attach multiple SCSI devices simultaneously, Scientific Linux 6.9 on IBM z Systems sometimes became unresponsive. This update fixes the zfcp device driver, and attaching multiple SCSI devices simultaneously now works as expected in the described scenario.

- On IBM z Systems, the tiqdio_call_inq_handlers() function in the Linux kernel incorrectly cleared the device state change indicator (DSCI) for the af_iucv devices using the HiperSockets transport with multiple input queues. Consequently, queue stalls on such devices occasionally occurred. With this update, tiqdio_call_inq_handlers() has been fixed to clear the DSCI only once, prior to scanning the queues. As a result, queue stalls for af_iucv devices using the HiperSockets transport no longer occur under the described circumstances.

- Previously, small data chunks caused the Stream Control Transmission Protocol (SCTP) to account the receiver_window (rwnd) values incorrectly when recovering from a 'zero-window situation'. As a consequence, window updates were not sent to the peer, and an artificial growth of rwnd could lead to packet drops. This update properly accounts such small data chunks and ignores the rwnd pressure values when reopening a window. As a result, window updates are now sent, and the announced rwnd reflects better the real state of the receive buffer.


Update the affected packages.

See Also

Plugin Details

Severity: Critical

ID: 106369

File Name: sl_20180125_kernel_on_SL6_x.nasl

Version: $Revision: 3.1 $

Type: local

Agent: unix

Published: 2018/01/26

Modified: 2018/01/26

Dependencies: 12634

Risk Information

Risk Factor: Critical


Base Score: 10

Vector: CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:C


Base Score: 9.8

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Vulnerability Information

CPE: x-cpe:/o:fermilab:scientific_linux

Required KB Items: Host/local_checks_enabled, Host/cpu, Host/RedHat/release, Host/RedHat/rpm-list

Patch Publication Date: 2018/01/25

Reference Information

CVE: CVE-2017-11176, CVE-2017-7542, CVE-2017-9074