The block subsystem in the Linux kernel before 5.14 mishandles reference counts, which allows local users to cause a denial of service (use-after-free) or possibly have unspecified other impacts via a crafted user space program related to the disk object reference count. References: https://lkml.org/lkml/2021/9/6/781 https://lkml.org/lkml/2021/10/18/485
This bug is now closed. Further updates for individual products will be reflected on the CVE page(s): https://access.redhat.com/security/cve/cve-2021-4150