kconfig.h: Include compiler types to avoid missed struct attributes

The header files for some structures could get included in such a way
that struct attributes (specifically __randomize_layout from path.h) would
be parsed as variable names instead of attributes. This could lead to
some instances of a structure being unrandomized, causing nasty GPFs, etc.

This patch makes sure the compiler_types.h header is included in
kconfig.h so that we've always got types and struct attributes defined,
since kconfig.h is included from the compiler command line.
Reported-by: NPatrick McLean <chutzpah@gentoo.org>
Root-caused-by: NMaciej S. Szmigiero <mail@maciej.szmigiero.name>
Suggested-by: NLinus Torvalds <torvalds@linux-foundation.org>
Tested-by: NMaciej S. Szmigiero <mail@maciej.szmigiero.name>
Fixes: 3859a271 ("randstruct: Mark various structs for randomization")
Signed-off-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

include/linux/kconfig.h

@@ -64,4 +64,7 @@
  */
 #define IS_ENABLED(option) __or(IS_BUILTIN(option), IS_MODULE(option))
 
+/* Make sure we always have all types and struct attributes defined. */
+#include <linux/compiler_types.h>
+
 #endif /* __LINUX_KCONFIG_H */