Commit f39f18f3 authored by Kees Cook's avatar Kees Cook
Browse files

randstruct: gcc-plugin: Fix attribute addition 

Based on changes in the 2021 public version of the randstruct
out-of-tree GCC plugin[1], more carefully update the attributes on
resulting decls, to avoid tripping checks in GCC 15's
comptypes_check_enum_int() when it has been configured with
"--enable-checking=misc":

arch/arm64/kernel/kexec_image.c:132:14: internal compiler error: in comptypes_check_enum_int, at c/c-typeck.cc:1519
  132 | const struct kexec_file_ops kexec_image_ops = {
      |              ^~~~~~~~~~~~~~
 internal_error(char const*, ...), at gcc/gcc/diagnostic-global-context.cc:517
 fancy_abort(char const*, int, char const*), at gcc/gcc/diagnostic.cc:1803
 comptypes_check_enum_int(tree_node*, tree_node*, bool*), at gcc/gcc/c/c-typeck.cc:1519
 ...

Link: https://archive.org/download/grsecurity/grsecurity-3.1-5.10.41-202105280954.patch.gz

 [1]
Reported-by: default avatarThiago Jung Bauermann <thiago.bauermann@linaro.org>
Closes: https://github.com/KSPP/linux/issues/367
Closes: https://lore.kernel.org/lkml/20250530000646.104457-1-thiago.bauermann@linaro.org/


Reported-by: default avatarIngo Saitz <ingo@hannover.ccc.de>
Closes: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1104745


Fixes: 313dd1b6 ("gcc-plugins: Add the randstruct plugin")
Tested-by: default avatarThiago Jung Bauermann <thiago.bauermann@linaro.org>
Link: https://lore.kernel.org/r/20250530221824.work.623-kees@kernel.org


Signed-off-by: default avatarKees Cook <kees@kernel.org>
parent 5c78e793

scripts/gcc-plugins/gcc-common.h

+32 −0
Original line number Diff line number Diff line
@@ -123,6 +123,38 @@ static inline tree build_const_char_string(int len, const char *str) 
	return cstr;

}



static inline void __add_type_attr(tree type, const char *attr, tree args)

{

	tree oldattr;



	if (type == NULL_TREE)

		return;

	oldattr = lookup_attribute(attr, TYPE_ATTRIBUTES(type));

	if (oldattr != NULL_TREE) {

		gcc_assert(TREE_VALUE(oldattr) == args || TREE_VALUE(TREE_VALUE(oldattr)) == TREE_VALUE(args));

		return;

	}



	TYPE_ATTRIBUTES(type) = copy_list(TYPE_ATTRIBUTES(type));

	TYPE_ATTRIBUTES(type) = tree_cons(get_identifier(attr), args, TYPE_ATTRIBUTES(type));

}



static inline void add_type_attr(tree type, const char *attr, tree args)

{

	tree main_variant = TYPE_MAIN_VARIANT(type);



	__add_type_attr(TYPE_CANONICAL(type), attr, args);

	__add_type_attr(TYPE_CANONICAL(main_variant), attr, args);

	__add_type_attr(main_variant, attr, args);



	for (type = TYPE_NEXT_VARIANT(main_variant); type; type = TYPE_NEXT_VARIANT(type)) {

		if (!lookup_attribute(attr, TYPE_ATTRIBUTES(type)))

			TYPE_ATTRIBUTES(type) = TYPE_ATTRIBUTES(main_variant);



		__add_type_attr(TYPE_CANONICAL(type), attr, args);

	}

}



#define PASS_INFO(NAME, REF, ID, POS)		\

struct register_pass_info NAME##_pass_info = {	\

	.pass = make_##NAME##_pass(),		\

scripts/gcc-plugins/randomize_layout_plugin.c

+11 −11
Original line number Diff line number Diff line
@@ -73,6 +73,9 @@ static tree handle_randomize_layout_attr(tree *node, tree name, tree args, int f 


	if (TYPE_P(*node)) {

		type = *node;

	} else if (TREE_CODE(*node) == FIELD_DECL) {

		*no_add_attrs = false;

		return NULL_TREE;

	} else {

		gcc_assert(TREE_CODE(*node) == TYPE_DECL);

		type = TREE_TYPE(*node);
@@ -348,15 +351,14 @@ static int relayout_struct(tree type) 
		TREE_CHAIN(newtree[i]) = newtree[i+1];

	TREE_CHAIN(newtree[num_fields - 1]) = NULL_TREE;



	add_type_attr(type, "randomize_performed", NULL_TREE);

	add_type_attr(type, "designated_init", NULL_TREE);

	if (has_flexarray)

		add_type_attr(type, "has_flexarray", NULL_TREE);



	main_variant = TYPE_MAIN_VARIANT(type);

	for (variant = main_variant; variant; variant = TYPE_NEXT_VARIANT(variant)) {

	for (variant = main_variant; variant; variant = TYPE_NEXT_VARIANT(variant))

		TYPE_FIELDS(variant) = newtree[0];

		TYPE_ATTRIBUTES(variant) = copy_list(TYPE_ATTRIBUTES(variant));

		TYPE_ATTRIBUTES(variant) = tree_cons(get_identifier("randomize_performed"), NULL_TREE, TYPE_ATTRIBUTES(variant));

		TYPE_ATTRIBUTES(variant) = tree_cons(get_identifier("designated_init"), NULL_TREE, TYPE_ATTRIBUTES(variant));

		if (has_flexarray)

			TYPE_ATTRIBUTES(type) = tree_cons(get_identifier("has_flexarray"), NULL_TREE, TYPE_ATTRIBUTES(type));

	}



	/*

	 * force a re-layout of the main variant
@@ -424,10 +426,8 @@ static void randomize_type(tree type) 
	if (lookup_attribute("randomize_layout", TYPE_ATTRIBUTES(TYPE_MAIN_VARIANT(type))) || is_pure_ops_struct(type))

		relayout_struct(type);



	for (variant = TYPE_MAIN_VARIANT(type); variant; variant = TYPE_NEXT_VARIANT(variant)) {

		TYPE_ATTRIBUTES(type) = copy_list(TYPE_ATTRIBUTES(type));

		TYPE_ATTRIBUTES(type) = tree_cons(get_identifier("randomize_considered"), NULL_TREE, TYPE_ATTRIBUTES(type));

	}

	add_type_attr(type, "randomize_considered", NULL_TREE);



#ifdef __DEBUG_PLUGIN

	fprintf(stderr, "Marking randomize_considered on struct %s\n", ORIG_TYPE_NAME(type));

#ifdef __DEBUG_VERBOSE