(RHSA-2018:1351) Moderate: kernel security and bug fix update

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

Security Fix(es):

• Kernel: error in exception handling leads to DoS (CVE-2018-8897)

For more details about the security issue(s), including the impact, a CVSS score, and other related information, refer to the CVE page(s) listed in the References section.

Red Hat would like to thank Nick Peterson (Everdox Tech LLC) and Andy Lutomirski for reporting this issue.

Bug Fix(es):

• If an NFSv3 client mounted a subdirectory of an exported file system, a directory entry to the mount hosting the export was incorrectly held even after clearing the cache. Consequently, attempts to unmount the subdirectory with the umount command failed with the EBUSY error. With this update, the underlying source code has been fixed, and the unmount operation now succeeds as expected in the described situation. (BZ#1538588)

• The kernel build requirements have been updated to the GNU Compiler Collection (GCC) compiler version that has the support for Retpolines. The Retpolines mechanism is a software construct that leverages specific knowledge of the underlying hardware to mitigate the branch target injection, also known as Spectre variant 2 vulnerability described in CVE-2017-5715. (BZ#1554254)