Makefile: Globally enable VLA warning
Now that Variable Length Arrays (VLAs) have been entirely removed[1]
from the kernel, enable the VLA warning globally. The only exceptions
to this are the KASan an UBSan tests which are explicitly checking that
VLAs trigger their respective tests.
[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: David Airlie <airlied@linux.ie>
Cc: linux-kbuild@vger.kernel.org
Cc: intel-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Kees Cook <keescook@chromium.org>
diff --git a/Makefile b/Makefile
index 19948e5..f1760e8 100644
--- a/Makefile
+++ b/Makefile
@@ -804,6 +804,9 @@
# warn about C99 declaration after statement
KBUILD_CFLAGS += $(call cc-option,-Wdeclaration-after-statement,)
+# Variable Length Arrays (VLAs) should not be used anywhere in the kernel
+KBUILD_CFLAGS += $(call cc-option,-Wvla)
+
# disable pointer signed / unsigned warnings in gcc 4.0
KBUILD_CFLAGS += $(call cc-disable-warning, pointer-sign)
diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
index 5794f10..1c2857f1 100644
--- a/drivers/gpu/drm/i915/Makefile
+++ b/drivers/gpu/drm/i915/Makefile
@@ -12,7 +12,7 @@
# Note the danger in using -Wall -Wextra is that when CI updates gcc we
# will most likely get a sudden build breakage... Hopefully we will fix
# new warnings before CI updates!
-subdir-ccflags-y := -Wall -Wextra -Wvla
+subdir-ccflags-y := -Wall -Wextra
subdir-ccflags-y += $(call cc-disable-warning, unused-parameter)
subdir-ccflags-y += $(call cc-disable-warning, type-limits)
subdir-ccflags-y += $(call cc-disable-warning, missing-field-initializers)
diff --git a/lib/Makefile b/lib/Makefile
index ca3f7eb..8e0aca8 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -53,7 +53,9 @@
obj-$(CONFIG_TEST_IDA) += test_ida.o
obj-$(CONFIG_TEST_KASAN) += test_kasan.o
CFLAGS_test_kasan.o += -fno-builtin
+CFLAGS_test_kasan.o += $(call cc-disable-warning, vla)
obj-$(CONFIG_TEST_UBSAN) += test_ubsan.o
+CFLAGS_test_ubsan.o += $(call cc-disable-warning, vla)
UBSAN_SANITIZE_test_ubsan.o := y
obj-$(CONFIG_TEST_KSTRTOX) += test-kstrtox.o
obj-$(CONFIG_TEST_LIST_SORT) += test_list_sort.o
diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn
index 8d53570..24b2fb1 100644
--- a/scripts/Makefile.extrawarn
+++ b/scripts/Makefile.extrawarn
@@ -52,7 +52,6 @@
warning-3 += -Wredundant-decls
warning-3 += -Wswitch-default
warning-3 += $(call cc-option, -Wpacked-bitfield-compat)
-warning-3 += $(call cc-option, -Wvla)
warning := $(warning-$(findstring 1, $(KBUILD_ENABLE_EXTRA_GCC_CHECKS)))
warning += $(warning-$(findstring 2, $(KBUILD_ENABLE_EXTRA_GCC_CHECKS)))