On Fri, Oct 18, 2019 at 10:13 AM Jann Horn <jannh@xxxxxxxxxx> wrote: > These things should probably be __always_inline or something like > that? If the compiler decides not to inline them (e.g. when called > from scs_thread_switch()), stuff will blow up, right? Correct. I'll change these to __always_inline in v2. I think there might be other places in the kernel where not inlining a static inline function would break things, but there's no need to add more. > This is different from the intended protection level according to > <https://clang.llvm.org/docs/ShadowCallStack.html#security>, which > talks about "a runtime that avoids exposing the address of the shadow > call stack to attackers that can read arbitrary memory". Of course, > that's extremely hard to implement in the context of the kernel, where > you can see all the memory management data structures and all physical > memory. Yes, the security guarantees in the kernel are different as hiding shadow stack pointers is more challenging. > You might want to write something in the cover letter about what the > benefits of this mechanism compared to STACKPROTECTOR are in the > context of the kernel, including a specific description of which types > of attacker capabilities this is supposed to defend against. Sure, I'll add something about that in v2. Thanks. Sami
