In the Linux kernel through 4.14.13, drivers/block/loop.c mishandles lo_release serialization, which allows attackers to cause a denial of service (__lock_acquire use-after-free) or possibly have unspecified other impact.
git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=ae6650163c66a7eff1acd6eb8b0f752dcfa8eba5
www.securityfocus.com/bid/102503
access.redhat.com/errata/RHSA-2018:2948
access.redhat.com/errata/RHSA-2018:3083
access.redhat.com/errata/RHSA-2018:3096
github.com/torvalds/linux/commit/ae6650163c66a7eff1acd6eb8b0f752dcfa8eba5
usn.ubuntu.com/3583-1/
usn.ubuntu.com/3583-2/
usn.ubuntu.com/3617-1/
usn.ubuntu.com/3617-2/
usn.ubuntu.com/3617-3/
usn.ubuntu.com/3619-1/
usn.ubuntu.com/3619-2/
usn.ubuntu.com/3632-1/