A locking issue was discovered in the tty subsystem of the Linux kernel through 5.9.13. drivers/tty/tty_jobctrl.c allows a use-after-free attack against TIOCSPGRP, aka CID-54ffccbf053b.
https://www.cisa.gov/news-events/ics-advisories/icsa-24-074-07
https://www.oracle.com/security-alerts/cpuoct2021.html
https://www.debian.org/security/2021/dsa-4843
https://security.netapp.com/advisory/ntap-20210122-0001/
https://lists.debian.org/debian-lts-announce/2021/03/msg00010.html
https://lists.debian.org/debian-lts-announce/2021/02/msg00018.html
http://www.openwall.com/lists/oss-security/2020/12/10/1
http://packetstormsecurity.com/files/164950/Kernel-Live-Patch-Security-Notice-LSN-0082-1.html
http://packetstormsecurity.com/files/160681/Linux-TIOCSPGRP-Broken-Locking.html