[ELSA-2018-4301] Unbreakable Enterprise kernel security update

[2.6.39-400.304.1]
- mnt: Prevent pivot_root from creating a loop in the mount tree (Eric W. Biederman) [Orabug: 26575709] {CVE-2014-7970} {CVE-2014-7970}
- vfs: more mnt_parent cleanups (Al Viro) [Orabug: 26575709] {CVE-2014-7970}
- vfs: new internal helper: mnt_has_parent(mnt) (Al Viro) [Orabug: 26575709] {CVE-2014-7970}
- ALSA: seq: Fix racy pool initializations (Takashi Iwai) [Orabug: 28459730] {CVE-2018-7566}
- xen-netback: calculate full_coalesce before the pre-estimation of ring buffer slots to consume (Dongli Zhang) [Orabug: 28818690]
- scsi: sg: allocate with __GFP_ZERO in sg_build_indirect() (Alexander Potapenko) [Orabug: 28892695] {CVE-2018-1000204}
- KVM: MTRR: remove MSR 0x2f8 (Andy Honig) [Orabug: 28901711] {CVE-2016-3713} {CVE-2016-3713}
- cdrom: fix improper type cast, which can leat to information leak. (Young_X) [Orabug: 28929788] {CVE-2018-16658} {CVE-2018-10940} {CVE-2018-18710}
- udf: Check component length before reading it (Jan Kara) [Orabug: 28941923] {CVE-2014-9728}
- udf: Verify symlink size before loading it (Shan Hai) [Orabug: 28941923] {CVE-2014-9728}
- udf: Verify i_size when loading inode (Shan Hai) [Orabug: 28941923] {CVE-2014-9728}
- floppy: Do not copy a kernel pointer to user memory in FDGETPRM ioctl (Andy Whitcroft) [Orabug: 28956549] {CVE-2018-7755} {CVE-2018-7755}
- crypto: salsa20 - fix blkcipher_walk API usage (Eric Biggers) [Orabug: 28976586] {CVE-2017-17805}
- crypto: hmac - require that the underlying hash algorithm is unkeyed (Eric Biggers) [Orabug: 28976655] {CVE-2017-17806}