On Mon, Aug 07, 2023 at 11:00:26PM +0100, Mark Brown wrote: > As discussed extensively in the changelog for the addition of this > syscall on x86 ("x86/shstk: Introduce map_shadow_stack syscall") the > existing mmap() and madvise() syscalls do not map entirely well onto the > security requirements for guarded control stacks since they lead to > windows where memory is allocated but not yet protected or stacks which > are not properly and safely initialised. Instead a new syscall > map_shadow_stack() has been defined which allocates and initialises a > shadow stack page. I guess I need to read the x86 discussion after all ;). Given that we won't have an mmap(PROT_SHADOW_STACK), are we going to have restrictions on mprotect()? E.g. it would be useful to reject a PROT_EXEC on the shadow stack. -- Catalin