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Message-ID: <20170201202347.GA75273@beast>
Date: Wed, 1 Feb 2017 12:23:47 -0800
From: Kees Cook <keescook@...omium.org>
To: Brad Spengler <spender@...ecurity.net>
Cc: Josh Triplett <josh@...htriplett.org>, PaX Team <pageexec@...email.hu>,
Emese Revfy <re.emese@...il.com>,
kernel-hardening@...ts.openwall.com
Subject: [PATCH] randstruct: Use -Werror=designated-init
GCC 5.1 and later supports -Werror=designated-init, which can be used with
randstruct to locate places where designated initializers are missing.
Suggested-by: Josh Triplett <josh@...htriplett.org>
Signed-off-by: Kees Cook <keescook@...omium.org>
---
Makefile | 3 +++
include/linux/compiler-gcc.h | 2 ++
scripts/gcc-plugins/randomize_layout_plugin.c | 1 +
3 files changed, 6 insertions(+)
diff --git a/Makefile b/Makefile
index f21d750fa022..1f94aba409b5 100644
--- a/Makefile
+++ b/Makefile
@@ -781,6 +781,9 @@ KBUILD_CFLAGS += $(call cc-option,-Werror=date-time)
# enforce correct pointer usage
KBUILD_CFLAGS += $(call cc-option,-Werror=incompatible-pointer-types)
+# Require designated initializers for all marked structures
+KBUILD_CFLAGS += $(call cc-option,-Werror=designated-init)
+
# use the deterministic mode of AR if available
KBUILD_ARFLAGS := $(call ar-option,D)
diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
index 3ae2773b0498..fc411495e534 100644
--- a/include/linux/compiler-gcc.h
+++ b/include/linux/compiler-gcc.h
@@ -197,6 +197,8 @@
#ifdef RANDSTRUCT_PLUGIN
#define __randomize_layout __attribute__((randomize_layout))
#define __no_randomize_layout __attribute__((no_randomize_layout))
+#else
+#define __randomize_layout __attribute__((designated_init))
#endif
#ifdef CONSTIFY_PLUGIN
diff --git a/scripts/gcc-plugins/randomize_layout_plugin.c b/scripts/gcc-plugins/randomize_layout_plugin.c
index 1f62fabc1141..9e314e4d9162 100644
--- a/scripts/gcc-plugins/randomize_layout_plugin.c
+++ b/scripts/gcc-plugins/randomize_layout_plugin.c
@@ -377,6 +377,7 @@ static int relayout_struct(tree type)
TYPE_FIELDS(variant) = list;
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));
}
--
2.7.4
--
Kees Cook
Pixel Security
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