In the Linux kernel before 5.2.3, drivers/block/floppy.c allows a denial of service by setup_format_params division-by-zero. Two consecutive ioctls can trigger the bug: the first one should set the drive geometry with .sect and .rate values that make F_SECT_PER_TRACK be zero. Next, the floppy format operation should be called. It can be triggered by an unprivileged local user even when a floppy disk has not been inserted. NOTE: QEMU creates the floppy device by default.
https://www.debian.org/security/2019/dsa-4497
https://www.debian.org/security/2019/dsa-4495
https://usn.ubuntu.com/4118-1/
https://usn.ubuntu.com/4117-1/
https://usn.ubuntu.com/4116-1/
https://usn.ubuntu.com/4115-1/
https://usn.ubuntu.com/4114-1/
https://security.netapp.com/advisory/ntap-20190905-0002/
https://seclists.org/bugtraq/2019/Aug/26
https://seclists.org/bugtraq/2019/Aug/18
https://seclists.org/bugtraq/2019/Aug/13
https://lists.debian.org/debian-lts-announce/2019/08/msg00017.html
https://lists.debian.org/debian-lts-announce/2019/08/msg00016.html
https://github.com/torvalds/linux/commit/f3554aeb991214cbfafd17d55e2bfddb50282e32
https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.2.3
http://packetstormsecurity.com/files/154951/Kernel-Live-Patch-Security-Notice-LSN-0058-1.html
http://packetstormsecurity.com/files/154408/Kernel-Live-Patch-Security-Notice-LSN-0055-1.html
http://lists.opensuse.org/opensuse-security-announce/2019-08/msg00056.html
http://lists.opensuse.org/opensuse-security-announce/2019-08/msg00055.html