On Fri, Jan 8, 2021 at 9:31 PM Arnd Bergmann <arnd@xxxxxxxxxx> wrote: > > On Fri, Jan 8, 2021 at 7:56 PM Andrey Konovalov <andreyknvl@xxxxxxxxxx> wrote: > > On Fri, Jan 8, 2021 at 5:09 AM Walter Wu <walter-zh.wu@xxxxxxxxxxxx> wrote: > > > > @@ -2,6 +2,12 @@ > > > CFLAGS_KASAN_NOSANITIZE := -fno-builtin > > > KASAN_SHADOW_OFFSET ?= $(CONFIG_KASAN_SHADOW_OFFSET) > > > > > > +ifdef CONFIG_KASAN_STACK > > > + stack_enable := 1 > > > +else > > > + stack_enable := 0 > > > +endif > > > + > > > > AFAIR, Arnd wanted to avoid having KASAN_STACK to be enabled by > > default when compiling with Clang, since Clang instrumentation leads > > to very large kernel stacks, which, in turn, lead to compile-time > > warnings. What I don't remember is why there are two configs. > > > > Arnd, is that correct? What was the reason behind having two configs? > > I think I just considered it cleaner than defining the extra variable in the > Makefile at the time, as this was the only place that referenced > CONFIG_KASAN_STACK. > > The '#if CONFIG_KASAN_STACK' (rather than #ifdef) that got added > later do make my version more confusing though, so I agree that > Walter's second patch improves it. > > Acked-by: Arnd Bergmann <arnd@xxxxxxxx> Got it, thanks! > On a related note: do you have any hope that clang will ever fix > https://bugs.llvm.org/show_bug.cgi?id=38809 and KASAN_STACK > can be enabled by default on clang without risking stack > overflows? Not sure :( I've filed this on KASAN bugzilla to not forget: https://bugzilla.kernel.org/show_bug.cgi?id=211139
