In the Linux kernel 4.12, 3.10, 2.6 and possibly earlier versions a race condition vulnerability exists in the sound system, this can lead to a deadlock and denial of service condition.
https://www.debian.org/security/2018/dsa-4187
https://usn.ubuntu.com/3798-2/
https://usn.ubuntu.com/3798-1/
https://usn.ubuntu.com/3631-2/
https://usn.ubuntu.com/3631-1/
https://access.redhat.com/errata/RHSA-2019:1483
https://access.redhat.com/errata/RHSA-2018:2390
https://access.redhat.com/errata/RHSA-2018:1062