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: Patrick McLean <[email protected]>
Root-caused-by: Maciej S. Szmigiero <[email protected]>
Suggested-by: Linus Torvalds <[email protected]>
Tested-by: Maciej S. Szmigiero <[email protected]>
Fixes: 3859a27 ("randstruct: Mark various structs for randomization")
Signed-off-by: Kees Cook <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

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 */