automatic structure layout randomization for all-function-pointer structs misses composite structs

[kees]

With -frandomize-layout-seed-file=..., this structure will correctly automatically be randomized as if it was marked with the randomize_layout attribute:

struct inner {
  int (a*)(int);
  int (b*)(void);
};

However, this will not:

struct compositve {
  struct inner inner;
  void (c*)(int);
};

The checking needs to examine composite structures as well.

[kees]

cc @bwendling

[llvmbot]

@llvm/issue-subscribers-clang-frontend

Author: Kees Cook (kees)

With `-frandomize-layout-seed-file=...`, this structure will correctly automatically be randomized as if it was marked with the `randomize_layout` attribute:

struct inner {
  int (a*)(int);
  int (b*)(void);
};

However, this will not:

struct compositve {
  struct inner inner;
  void (c*)(int);
};

The checking needs to examine composite structures as well.