Linux < 4.20.14 - Virtual Address 0 is Mappable via Privileged write() to /proc/*/mem Exploit

Linux memrw - accessremotevm - accessremotevm - getuserpagesremote - getuserpageslocked - getuserpages - findextendvma Then, if the VMA in question has the VMGROWSDOWN flag set: expandstack - expanddownwards - securitymmapaddr - capmmapaddr This, if the address is below dacmmapminaddr, does a...