Re: [PATCH 06/18] add support for Clang's Shadow Call Stack (SCS)

Joe Perches
2019-10-18T16:58:36Z

On Fri, 2019-10-18 at 09:10 -0700, Sami Tolvanen wrote:
> This change adds generic support for Clang's Shadow Call Stack, which
> uses a shadow stack to protect return addresses from being overwritten
> by an attacker
[]
> .diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h
[]
> @@ -42,3 +42,5 @@
> * compilers, like ICC.
> */
> #define barrier() __asm__ __volatile__("" : : : "memory")
> +
> +#define __noscs __attribute__((no_sanitize("shadow-call-stack")))

trivia:

This should likely use the __ prefix and suffix form:

#define __noscs __attribute__((__no_sanitize__("shadow-call-stack")))

as should the __no_sanitize_address above this

> diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h
[]
> @@ -202,6 +202,10 @@ struct ftrace_likely_data {
> # define randomized_struct_fields_end
> #endif
>
> +#ifndef __noscs
> +# define __noscs
> +#endif
> +
> #ifndef asm_volatile_goto
> #define asm_volatile_goto(x...) asm goto(x)
> #endif