Merge tag 'var-init-v5.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull automatic variable initialization updates from Kees Cook:
 "This adds the "zero" init option from Clang, which is being used
  widely in production builds of Android and Chrome OS (though it also
  keeps the "pattern" init, which is better for debug builds).

   - Introduce CONFIG_INIT_STACK_ALL_ZERO (Alexander Potapenko)"

* tag 'var-init-v5.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  security: allow using Clang's zero initialization for stack variables

1 files changed, 11 insertions, 2 deletions

diff --git a/Makefile b/Makefile
index aef9ca61caf0..09c1bd1fcb64 100644
--- a/Makefile
+++ b/Makefile
@@ -803,11 +803,20 @@ KBUILD_CFLAGS	+= -fomit-frame-pointer
 endif
 endif
 
-# Initialize all stack variables with a pattern, if desired.
-ifdef CONFIG_INIT_STACK_ALL
+# Initialize all stack variables with a 0xAA pattern.
+ifdef CONFIG_INIT_STACK_ALL_PATTERN
 KBUILD_CFLAGS	+= -ftrivial-auto-var-init=pattern
 endif
 
+# Initialize all stack variables with a zero value.
+ifdef CONFIG_INIT_STACK_ALL_ZERO
+# Future support for zero initialization is still being debated, see
+# https://bugs.llvm.org/show_bug.cgi?id=45497. These flags are subject to being
+# renamed or dropped.
+KBUILD_CFLAGS	+= -ftrivial-auto-var-init=zero
+KBUILD_CFLAGS	+= -enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang
+endif
+
 DEBUG_CFLAGS	:= $(call cc-option, -fno-var-tracking-assignments)
 
 ifdef CONFIG_DEBUG_INFO