Address space layout randomization PaX
1 address space layout randomization 1.1 randomized stack base 1.2 randomized mmap() base 1.3 randomized et_exec base address space layout randomization address space layout randomization, or aslr, technique of countering arbitrary execution of code, or ret2libc attacks. these attacks involve executing existing code out of order intended programmer. fig. 2 distance between various areas of memory randomly selected, indicated half-head arrow. example, gap between stack , top of memory random in magnitude. aslr provided in pax shuffles stack base , heap base around in virtual memory when enabled. optionally randomizes mmap() base , executable base of programs. substantially lowers probability of successful attack requiring attacking code guess locations of these areas. fig. 2 shows qualitative views of process address spaces address space layout randomization. half-head arrows indicate random gap between various areas of virtual memory. @ point when kernel initializes process, length of...