Messages in this thread | | | Date | Fri, 08 Oct 2021 11:46:55 -0700 (PDT) | Subject | Re: [PATCH] kasan: Always respect CONFIG_KASAN_STACK | From | Palmer Dabbelt <> |
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On Thu, 23 Sep 2021 07:59:46 PDT (-0700), nathan@kernel.org wrote: > On Thu, Sep 23, 2021 at 12:07:17PM +0200, Marco Elver wrote: >> On Wed, 22 Sept 2021 at 22:55, Nathan Chancellor <nathan@kernel.org> wrote: >> > Currently, the asan-stack parameter is only passed along if >> > CFLAGS_KASAN_SHADOW is not empty, which requires KASAN_SHADOW_OFFSET to >> > be defined in Kconfig so that the value can be checked. In RISC-V's >> > case, KASAN_SHADOW_OFFSET is not defined in Kconfig, which means that >> > asan-stack does not get disabled with clang even when CONFIG_KASAN_STACK >> > is disabled, resulting in large stack warnings with allmodconfig: >> > >> > drivers/video/fbdev/omap2/omapfb/displays/panel-lgphilips-lb035q02.c:117:12: >> > error: stack frame size (14400) exceeds limit (2048) in function >> > 'lb035q02_connect' [-Werror,-Wframe-larger-than] >> > static int lb035q02_connect(struct omap_dss_device *dssdev) >> > ^ >> > 1 error generated. >> > >> > Ensure that the value of CONFIG_KASAN_STACK is always passed along to >> > the compiler so that these warnings do not happen when >> > CONFIG_KASAN_STACK is disabled. >> > >> > Link: https://github.com/ClangBuiltLinux/linux/issues/1453 >> > References: 6baec880d7a5 ("kasan: turn off asan-stack for clang-8 and earlier") >> > Signed-off-by: Nathan Chancellor <nathan@kernel.org> >> >> Reviewed-by: Marco Elver <elver@google.com> > > Thanks! > >> [ Which tree are you planning to take it through? ] > > Gah, I was intending for it to go through -mm, then I cc'd neither > Andrew nor linux-mm... :/ Andrew, do you want me to resend or can you > grab it from LKML?
Acked-by: Palmer Dabbelt <palmerdabbelt@google.com>
(assuming you still want it through somewhere else)
>> Note, arch/riscv/include/asm/kasan.h mentions KASAN_SHADOW_OFFSET in >> comment (copied from arm64). Did RISC-V just forget to copy over the >> Kconfig option? > > I do see it defined in that file as well but you are right that they did > not copy the Kconfig logic, even though it was present in the tree when > RISC-V KASAN was implemented. Perhaps they should so that they get > access to the other flags in the "else" branch?
Ya, looks like we just screwed this up. I'm seeing some warnings like
cc1: warning: ‘-fsanitize=kernel-address’ with stack protection is not supported without ‘-fasan-shadow-offset=’ for this target
which is how I ended up here, I'm assuming that's what you're talking about here? LMK if you were planning on sending along a fix or if you want me to go figure it out.
> >> > --- >> > scripts/Makefile.kasan | 3 ++- >> > 1 file changed, 2 insertions(+), 1 deletion(-) >> > >> > diff --git a/scripts/Makefile.kasan b/scripts/Makefile.kasan >> > index 801c415bac59..b9e94c5e7097 100644 >> > --- a/scripts/Makefile.kasan >> > +++ b/scripts/Makefile.kasan >> > @@ -33,10 +33,11 @@ else >> > CFLAGS_KASAN := $(CFLAGS_KASAN_SHADOW) \ >> > $(call cc-param,asan-globals=1) \ >> > $(call cc-param,asan-instrumentation-with-call-threshold=$(call_threshold)) \ >> > - $(call cc-param,asan-stack=$(stack_enable)) \ >> > $(call cc-param,asan-instrument-allocas=1) >> > endif >> > >> > +CFLAGS_KASAN += $(call cc-param,asan-stack=$(stack_enable)) >> > + >> > endif # CONFIG_KASAN_GENERIC >> > >> > ifdef CONFIG_KASAN_SW_TAGS >> > >> > base-commit: 4057525736b159bd456732d11270af2cc49ec21f >> > -- >> > 2.33.0.514.g99c99ed825 >> > >> >
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