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>
This commit is contained in:
Kees Cook 2018-06-25 15:59:34 -07:00
parent 81b4568348
commit 0bb95f80a3
4 changed files with 6 additions and 2 deletions

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@ -804,6 +804,9 @@ NOSTDINC_FLAGS += -nostdinc -isystem $(shell $(CC) -print-file-name=include)
# 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)

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@ -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)

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@ -53,7 +53,9 @@ obj-$(CONFIG_TEST_HASH) += test_hash.o test_siphash.o
obj-$(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

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@ -52,7 +52,6 @@ warning-3 += -Wpointer-arith
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)))