Related Vulnerabilities: CVE-2021-46910  

DescriptionA flaw was found in kmap_local() in the Linux Kernel that doubles the number of per-CPU fixmap slots allocated for kmap_local(). This causes the fixmap region to grow downwards beyond the start of its reserved window if the supported number of CPUs is large, and collide with the newly added virtual DT mapping right below it.A flaw was found in kmap_local() in the Linux Kernel that doubles the number of per-CPU fixmap slots allocated for kmap_local(). This causes the fixmap region to grow downwards beyond the start of its reserved window if the supported number of CPUs is large, and collide with the newly added virtual DT mapping right below it.