2020-05-28 17:23:30

by Andrey Konovalov

Subject: [PATCH] kasan: fix clang compilation warning due to stack protector

KASAN uses a single cc-option invocation to disable both conserve-stack
and stack-protector flags. The former flag is not present in Clang, which
causes cc-option to fail, and results in stack-protector being enabled.

Fix by using separate cc-option calls for each flag. Also collect all
flags in a variable to avoid calling cc-option multiple times for
different files.

Reported-by: Qian Cai <[email protected]>
Signed-off-by: Andrey Konovalov <[email protected]>
---
mm/kasan/Makefile | 21 +++++++++++++--------
1 file changed, 13 insertions(+), 8 deletions(-)

diff --git a/mm/kasan/Makefile b/mm/kasan/Makefile
index de3121848ddf..bf6f7b1f6b18 100644
--- a/mm/kasan/Makefile
+++ b/mm/kasan/Makefile
@@ -15,14 +15,19 @@ CFLAGS_REMOVE_tags_report.o = $(CC_FLAGS_FTRACE)

# Function splitter causes unnecessary splits in __asan_load1/__asan_store1
# see: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63533
-CFLAGS_common.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -DDISABLE_BRANCH_PROFILING
-CFLAGS_generic.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -DDISABLE_BRANCH_PROFILING
-CFLAGS_generic_report.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -DDISABLE_BRANCH_PROFILING
-CFLAGS_init.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -DDISABLE_BRANCH_PROFILING
-CFLAGS_quarantine.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -DDISABLE_BRANCH_PROFILING
-CFLAGS_report.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -DDISABLE_BRANCH_PROFILING
-CFLAGS_tags.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -DDISABLE_BRANCH_PROFILING
-CFLAGS_tags_report.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -DDISABLE_BRANCH_PROFILING
+CC_FLAGS_KASAN_CONFLICT := $(call cc-option, -fno-conserve-stack)
+CC_FLAGS_KASAN_CONFLICT += $(call cc-option, -fno-stack-protector)
+# Disable branch tracing to avoid recursion.
+CC_FLAGS_KASAN_CONFLICT += -DDISABLE_BRANCH_PROFILING
+
+CFLAGS_common.o := $(CC_FLAGS_KASAN_CONFLICT)
+CFLAGS_generic.o := $(CC_FLAGS_KASAN_CONFLICT)
+CFLAGS_generic_report.o := $(CC_FLAGS_KASAN_CONFLICT)
+CFLAGS_init.o := $(CC_FLAGS_KASAN_CONFLICT)
+CFLAGS_quarantine.o := $(CC_FLAGS_KASAN_CONFLICT)
+CFLAGS_report.o := $(CC_FLAGS_KASAN_CONFLICT)
+CFLAGS_tags.o := $(CC_FLAGS_KASAN_CONFLICT)
+CFLAGS_tags_report.o := $(CC_FLAGS_KASAN_CONFLICT)

obj-$(CONFIG_KASAN) := common.o init.o report.o
obj-$(CONFIG_KASAN_GENERIC) += generic.o generic_report.o quarantine.o
--
2.27.0.rc0.183.gde8f92d652-goog

2020-05-29 15:01:06

by Marco Elver

Subject: Re: [PATCH] kasan: fix clang compilation warning due to stack protector

On Thu, 28 May 2020 at 19:20, 'Andrey Konovalov' via kasan-dev
<[email protected]> wrote:
>
> KASAN uses a single cc-option invocation to disable both conserve-stack
> and stack-protector flags. The former flag is not present in Clang, which
> causes cc-option to fail, and results in stack-protector being enabled.
>
> Fix by using separate cc-option calls for each flag. Also collect all
> flags in a variable to avoid calling cc-option multiple times for
> different files.
>
> Reported-by: Qian Cai <[email protected]>
> Signed-off-by: Andrey Konovalov <[email protected]>
> ---

Thank you! I was about to send an almost identical patch, as I
encountered this when using clang.

Reviewed-by: Marco Elver <[email protected]>

> mm/kasan/Makefile | 21 +++++++++++++--------
> 1 file changed, 13 insertions(+), 8 deletions(-)
>
> diff --git a/mm/kasan/Makefile b/mm/kasan/Makefile
> index de3121848ddf..bf6f7b1f6b18 100644
> --- a/mm/kasan/Makefile
> +++ b/mm/kasan/Makefile
> @@ -15,14 +15,19 @@ CFLAGS_REMOVE_tags_report.o = $(CC_FLAGS_FTRACE)
>
> # Function splitter causes unnecessary splits in __asan_load1/__asan_store1
> # see: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63533
> -CFLAGS_common.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -DDISABLE_BRANCH_PROFILING
> -CFLAGS_generic.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -DDISABLE_BRANCH_PROFILING
> -CFLAGS_generic_report.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -DDISABLE_BRANCH_PROFILING
> -CFLAGS_init.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -DDISABLE_BRANCH_PROFILING
> -CFLAGS_quarantine.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -DDISABLE_BRANCH_PROFILING
> -CFLAGS_report.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -DDISABLE_BRANCH_PROFILING
> -CFLAGS_tags.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -DDISABLE_BRANCH_PROFILING
> -CFLAGS_tags_report.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -DDISABLE_BRANCH_PROFILING
> +CC_FLAGS_KASAN_CONFLICT := $(call cc-option, -fno-conserve-stack)
> +CC_FLAGS_KASAN_CONFLICT += $(call cc-option, -fno-stack-protector)
> +# Disable branch tracing to avoid recursion.
> +CC_FLAGS_KASAN_CONFLICT += -DDISABLE_BRANCH_PROFILING

Note that maybe CC_FLAGS_KASAN_RUNTIME could be a better name, because
other flags added in future might not be conflict-related. But until
that future, it doesn't really matter.

> +CFLAGS_common.o := $(CC_FLAGS_KASAN_CONFLICT)
> +CFLAGS_generic.o := $(CC_FLAGS_KASAN_CONFLICT)
> +CFLAGS_generic_report.o := $(CC_FLAGS_KASAN_CONFLICT)
> +CFLAGS_init.o := $(CC_FLAGS_KASAN_CONFLICT)
> +CFLAGS_quarantine.o := $(CC_FLAGS_KASAN_CONFLICT)
> +CFLAGS_report.o := $(CC_FLAGS_KASAN_CONFLICT)
> +CFLAGS_tags.o := $(CC_FLAGS_KASAN_CONFLICT)
> +CFLAGS_tags_report.o := $(CC_FLAGS_KASAN_CONFLICT)
>
> obj-$(CONFIG_KASAN) := common.o init.o report.o
> obj-$(CONFIG_KASAN_GENERIC) += generic.o generic_report.o quarantine.o
> --
> 2.27.0.rc0.183.gde8f92d652-goog
>
> --
> You received this message because you are subscribed to the Google Groups "kasan-dev" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to [email protected].
> To view this discussion on the web visit https://groups.google.com/d/msgid/kasan-dev/ced83584eec86a1a9ce264013cf6c0da5e0add6a.1590686292.git.andreyknvl%40google.com.

2020-05-29 19:15:55

by Andrey Konovalov

Subject: Re: [PATCH] kasan: fix clang compilation warning due to stack protector

On Fri, May 29, 2020 at 4:56 PM Marco Elver <[email protected]> wrote:
>
> On Thu, 28 May 2020 at 19:20, 'Andrey Konovalov' via kasan-dev
> <[email protected]> wrote:
> >
> > KASAN uses a single cc-option invocation to disable both conserve-stack
> > and stack-protector flags. The former flag is not present in Clang, which
> > causes cc-option to fail, and results in stack-protector being enabled.
> >
> > Fix by using separate cc-option calls for each flag. Also collect all
> > flags in a variable to avoid calling cc-option multiple times for
> > different files.
> >
> > Reported-by: Qian Cai <[email protected]>
> > Signed-off-by: Andrey Konovalov <[email protected]>
> > ---
>
> Thank you! I was about to send an almost identical patch, as I
> encountered this when using clang.
>
> Reviewed-by: Marco Elver <[email protected]>
>
> > mm/kasan/Makefile | 21 +++++++++++++--------
> > 1 file changed, 13 insertions(+), 8 deletions(-)
> >
> > diff --git a/mm/kasan/Makefile b/mm/kasan/Makefile
> > index de3121848ddf..bf6f7b1f6b18 100644
> > --- a/mm/kasan/Makefile
> > +++ b/mm/kasan/Makefile
> > @@ -15,14 +15,19 @@ CFLAGS_REMOVE_tags_report.o = $(CC_FLAGS_FTRACE)
> >
> > # Function splitter causes unnecessary splits in __asan_load1/__asan_store1
> > # see: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63533
> > -CFLAGS_common.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -DDISABLE_BRANCH_PROFILING
> > -CFLAGS_generic.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -DDISABLE_BRANCH_PROFILING
> > -CFLAGS_generic_report.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -DDISABLE_BRANCH_PROFILING
> > -CFLAGS_init.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -DDISABLE_BRANCH_PROFILING
> > -CFLAGS_quarantine.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -DDISABLE_BRANCH_PROFILING
> > -CFLAGS_report.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -DDISABLE_BRANCH_PROFILING
> > -CFLAGS_tags.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -DDISABLE_BRANCH_PROFILING
> > -CFLAGS_tags_report.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -DDISABLE_BRANCH_PROFILING
> > +CC_FLAGS_KASAN_CONFLICT := $(call cc-option, -fno-conserve-stack)
> > +CC_FLAGS_KASAN_CONFLICT += $(call cc-option, -fno-stack-protector)
> > +# Disable branch tracing to avoid recursion.
> > +CC_FLAGS_KASAN_CONFLICT += -DDISABLE_BRANCH_PROFILING
>
> Note that maybe CC_FLAGS_KASAN_RUNTIME could be a better name, because
> other flags added in future might not be conflict-related. But until
> that future, it doesn't really matter.

CC_FLAGS_KASAN_RUNTIME is a better name, sent v2, thanks!

>
> > +CFLAGS_common.o := $(CC_FLAGS_KASAN_CONFLICT)
> > +CFLAGS_generic.o := $(CC_FLAGS_KASAN_CONFLICT)
> > +CFLAGS_generic_report.o := $(CC_FLAGS_KASAN_CONFLICT)
> > +CFLAGS_init.o := $(CC_FLAGS_KASAN_CONFLICT)
> > +CFLAGS_quarantine.o := $(CC_FLAGS_KASAN_CONFLICT)
> > +CFLAGS_report.o := $(CC_FLAGS_KASAN_CONFLICT)
> > +CFLAGS_tags.o := $(CC_FLAGS_KASAN_CONFLICT)
> > +CFLAGS_tags_report.o := $(CC_FLAGS_KASAN_CONFLICT)
> >
> > obj-$(CONFIG_KASAN) := common.o init.o report.o
> > obj-$(CONFIG_KASAN_GENERIC) += generic.o generic_report.o quarantine.o
> > --
> > 2.27.0.rc0.183.gde8f92d652-goog
> >
> > --
> > You received this message because you are subscribed to the Google Groups "kasan-dev" group.
> > To unsubscribe from this group and stop receiving emails from it, send an email to [email protected].
> > To view this discussion on the web visit https://groups.google.com/d/msgid/kasan-dev/ced83584eec86a1a9ce264013cf6c0da5e0add6a.1590686292.git.andreyknvl%40google.com.