The sctp_do_peeloff function in net/sctp/socket.c in the Linux kernel before 4.14 does not check whether the intended netns is used in a peel-off action, which allows local users to cause a denial of service (use-after-free and system crash) or possibly have unspecified other impact via crafted system calls.
https://usn.ubuntu.com/3583-2/
https://usn.ubuntu.com/3583-1/
https://usn.ubuntu.com/3582-2/
https://usn.ubuntu.com/3582-1/
https://usn.ubuntu.com/3581-3/
https://usn.ubuntu.com/3581-2/
https://usn.ubuntu.com/3581-1/
https://source.android.com/security/bulletin/pixel/2018-04-01
https://patchwork.ozlabs.org/patch/827077/
https://lists.debian.org/debian-lts-announce/2017/12/msg00004.html
https://github.com/torvalds/linux/commit/df80cd9b28b9ebaa284a41df611dbf3a2d05ca74
https://bugzilla.redhat.com/show_bug.cgi?id=1513345
http://www.securityfocus.com/bid/101877
http://seclists.org/oss-sec/2017/q4/282
http://lists.opensuse.org/opensuse-security-announce/2018-01/msg00007.html