A flaw was found in the get_gate_page in mm/gup.c in the Linux kernel, where it allows privilege escalation due to incorrect reference counting (caused by gate page mishandling) of the struct page that backs the vsyscall page. The result is a refcount underflow. This flaw is triggered by any 64-bit process that can use ptrace() or process_vm_readv(). The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability.