From: Kees Cook <kees@kernel.org>
Date: Sat, 3 May 2025 18:46:20 +0000 (-0700)
Subject: integer-wrap: Force full rebuild when .scl file changes
X-Git-Tag: v6.16-rc1~151^2~7
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=11bb1678e249e51cd748e8f91e5241b3ce71da3a;p=thirdparty%2Fkernel%2Flinux.git

integer-wrap: Force full rebuild when .scl file changes

Since the integer wrapping sanitizer's behavior depends on its associated
.scl file, we must force a full rebuild if the file changes. If not,
instrumentation may differ between targets based on when they were built.

Generate a new header file, integer-wrap.h, any time the Clang .scl
file changes. Include the header file in compiler-version.h when its
associated feature name, INTEGER_WRAP, is defined. This will be picked
up by fixdep and force rebuilds where needed.

Acked-by: Justin Stitt <justinstitt@google.com>
Link: https://lore.kernel.org/r/20250503184623.2572355-3-kees@kernel.org
Reviewed-by: Nicolas Schier <n.schier@avm.de>
Signed-off-by: Kees Cook <kees@kernel.org>
---

diff --git a/include/linux/compiler-version.h b/include/linux/compiler-version.h
index 4b9d39b376503..ac1665a98a15d 100644
--- a/include/linux/compiler-version.h
+++ b/include/linux/compiler-version.h
@@ -32,3 +32,13 @@
 #ifdef RANDSTRUCT
 #include <generated/randstruct_hash.h>
 #endif
+
+/*
+ * If any external changes affect Clang's integer wrapping sanitizer
+ * behavior, a full rebuild is needed as the coverage for wrapping types
+ * may have changed, which may impact the expected behaviors that should
+ * not differ between compilation units.
+ */
+#ifdef INTEGER_WRAP
+#include <generated/integer-wrap.h>
+#endif
diff --git a/scripts/Makefile.ubsan b/scripts/Makefile.ubsan
index 9e35198edbf0d..653f7117819ca 100644
--- a/scripts/Makefile.ubsan
+++ b/scripts/Makefile.ubsan
@@ -15,6 +15,7 @@ ubsan-cflags-$(CONFIG_UBSAN_TRAP)		+= $(call cc-option,-fsanitize-trap=undefined
 export CFLAGS_UBSAN := $(ubsan-cflags-y)
 
 ubsan-integer-wrap-cflags-$(CONFIG_UBSAN_INTEGER_WRAP)     +=	\
+	-DINTEGER_WRAP						\
 	-fsanitize-undefined-ignore-overflow-pattern=all	\
 	-fsanitize=signed-integer-overflow			\
 	-fsanitize=unsigned-integer-overflow			\
diff --git a/scripts/basic/Makefile b/scripts/basic/Makefile
index dd289a6725aca..fb8e2c38fbc78 100644
--- a/scripts/basic/Makefile
+++ b/scripts/basic/Makefile
@@ -14,3 +14,8 @@ cmd_create_randstruct_seed = \
 $(obj)/randstruct.seed: $(gen-randstruct-seed) FORCE
 	$(call if_changed,create_randstruct_seed)
 always-$(CONFIG_RANDSTRUCT) += randstruct.seed
+
+# integer-wrap: if the .scl file changes, we need to do a full rebuild.
+$(obj)/../../include/generated/integer-wrap.h: $(srctree)/scripts/integer-wrap-ignore.scl FORCE
+	$(call if_changed,touch)
+always-$(CONFIG_UBSAN_INTEGER_WRAP) += ../../include/generated/integer-wrap.h