Messages in this thread Patch in this message | | | From | Linus Torvalds <> | Date | Wed, 8 Jun 2022 16:59:29 -0700 | Subject | Re: [PATCH] s390: disable -Warray-bounds |
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On Wed, Jun 8, 2022 at 2:33 PM Kees Cook <keescook@chromium.org> wrote: > > I and others have been working through a bunch of them, though yes, > they're not all fixed yet. I've been trying to track it here[1], but > many of those fixes are only in -next.
Hmm. Even with that disabled, I get a few warnings I *really* would want to get rid of.
The one in ipuv3-crtc.c seems valid about "address used as boolean is always true".
The 'dangling-pointer' warning does seem interesting, but not when the compiler does as bad a job as gcc seems to do.
See the attached patch for
(a) make the s390 "use -Wno-array-bounds for gcc-12" be generic
(b) fix the ipuv3-crtc.c one. IMX people?
(c) disable -Wdangling-pointer entirely for now
but that still leaves the netfs_i_context games, which gcc-12 is very unhappy about:
In function ‘fortify_memset_chk’, inlined from ‘netfs_i_context_init’ at ./include/linux/netfs.h:327:2, inlined from ‘afs_set_netfs_context’ at fs/afs/inode.c:61:2, inlined from ‘afs_inode_init_from_status’ at fs/afs/inode.c:139:2: ./include/linux/fortify-string.h:258:25: error: call to ‘__write_overflow_field’ declared with attribute warning: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror=attribute-warning]
and I do kind of agree with the compiler in that case. That code should have some kind of
struct container { struct inode inode; struct netfs_i_context ctx; };
thing, and aim to do that instead of the pointer arithmetic games.
Ceph seems to trigger the exact same thing.
There's also an annoying mlx5 issue, with gcc apparently not tracking the usage of
struct lag_tracker tracker;
well enough (it's never used if do_bond is false, but probably some inlining change means that gcc doesn't see that).
DavidH - mind looking at the netfs_i_context_init() thing?
I'd like to use something more surgical than CONFIG_CC_NO_ARRAY_BOUNDS, but considering the s390 issues, it may not even be worth it. Kees, just how far away are we from that being ok on x86-64?
I did consider making CONFIG_CC_NO_ARRAY_BOUNDS be more akin to
config CC_NO_ARRAY_BOUNDS bool depends on CC_IS_GCC depends on GCC_VERSION >= 120000 && GCC_VERSION < 130000 default GCC12_NO_ARRAY_BOUNDS
and then s390 and any subsystem that triggers the -Warray-bounds problem can do
select GCC12_NO_ARRAY_BOUNDS
to show that they have issues with the new gcc12 rules.
That would be at least a bit more surgical..
Linus Makefile | 4 ++++ arch/s390/Makefile | 10 +--------- drivers/gpu/drm/imx/ipuv3-crtc.c | 2 +- init/Kconfig | 5 +++++ 4 files changed, 11 insertions(+), 10 deletions(-)
diff --git a/Makefile b/Makefile index c43d825a3c4c..b2e93c1a8021 100644 --- a/Makefile +++ b/Makefile @@ -788,6 +788,7 @@ stackp-flags-$(CONFIG_STACKPROTECTOR_STRONG) := -fstack-protector-strong KBUILD_CFLAGS += $(stackp-flags-y) KBUILD_CFLAGS-$(CONFIG_WERROR) += -Werror +KBUILD_CFLAGS-$(CONFIG_CC_NO_ARRAY_BOUNDS) += -Wno-array-bounds KBUILD_CFLAGS += $(KBUILD_CFLAGS-y) $(CONFIG_CC_IMPLICIT_FALLTHROUGH) ifdef CONFIG_CC_IS_CLANG @@ -805,6 +806,9 @@ endif KBUILD_CFLAGS += $(call cc-disable-warning, unused-but-set-variable) KBUILD_CFLAGS += $(call cc-disable-warning, unused-const-variable) +# These result in bogus false positives +KBUILD_CFLAGS += $(call cc-disable-warning, dangling-pointer) + ifdef CONFIG_FRAME_POINTER KBUILD_CFLAGS += -fno-omit-frame-pointer -fno-optimize-sibling-calls else diff --git a/arch/s390/Makefile b/arch/s390/Makefile index d73611b35164..e1abb0d03824 100644 --- a/arch/s390/Makefile +++ b/arch/s390/Makefile @@ -32,15 +32,7 @@ KBUILD_CFLAGS_DECOMPRESSOR += -fno-stack-protector KBUILD_CFLAGS_DECOMPRESSOR += $(call cc-disable-warning, address-of-packed-member) KBUILD_CFLAGS_DECOMPRESSOR += $(if $(CONFIG_DEBUG_INFO),-g) KBUILD_CFLAGS_DECOMPRESSOR += $(if $(CONFIG_DEBUG_INFO_DWARF4), $(call cc-option, -gdwarf-4,)) - -ifdef CONFIG_CC_IS_GCC - ifeq ($(call cc-ifversion, -ge, 1200, y), y) - ifeq ($(call cc-ifversion, -lt, 1300, y), y) - KBUILD_CFLAGS += $(call cc-disable-warning, array-bounds) - KBUILD_CFLAGS_DECOMPRESSOR += $(call cc-disable-warning, array-bounds) - endif - endif -endif +KBUILD_CFLAGS_DECOMPRESSOR += $(if $(CC_NO_ARRAY_BOUNDS),-Wno-array-bounds) UTS_MACHINE := s390x STACK_SIZE := $(if $(CONFIG_KASAN),65536,16384) diff --git a/drivers/gpu/drm/imx/ipuv3-crtc.c b/drivers/gpu/drm/imx/ipuv3-crtc.c index 9c8829f945b2..f7863d6dea80 100644 --- a/drivers/gpu/drm/imx/ipuv3-crtc.c +++ b/drivers/gpu/drm/imx/ipuv3-crtc.c @@ -69,7 +69,7 @@ static void ipu_crtc_disable_planes(struct ipu_crtc *ipu_crtc, drm_atomic_crtc_state_for_each_plane(plane, old_crtc_state) { if (plane == &ipu_crtc->plane[0]->base) disable_full = true; - if (&ipu_crtc->plane[1] && plane == &ipu_crtc->plane[1]->base) + if (ipu_crtc->plane[1] && plane == &ipu_crtc->plane[1]->base) disable_partial = true; } diff --git a/init/Kconfig b/init/Kconfig index c984afc489de..ccb1302d6edd 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -885,6 +885,11 @@ config CC_IMPLICIT_FALLTHROUGH default "-Wimplicit-fallthrough=5" if CC_IS_GCC && $(cc-option,-Wimplicit-fallthrough=5) default "-Wimplicit-fallthrough" if CC_IS_CLANG && $(cc-option,-Wunreachable-code-fallthrough) +config CC_NO_ARRAY_BOUNDS + bool + depends on CC_IS_GCC + default y if GCC_VERSION >= 120000 && GCC_VERSION < 130000 + # # For architectures that know their GCC __int128 support is sound # | |