In the upcoming gcc-7 release, the -fsanitize=kernel-address option implies -fsanitize-address-use-after-scope, which relies on the definition of two global functions, causing many link errors if they are not defined, e.g: arch/x86/built-in.o: In function `x86_pmu_handle_irq': (.text+0x88e6): undefined reference to `__asan_unpoison_stack_memory' arch/x86/built-in.o: In function `x86_pmu_handle_irq': (.text+0x8ad7): undefined reference to `__asan_poison_stack_memory' kernel/built-in.o: In function `perf_tp_event': (.text+0x225472): undefined reference to `__asan_unpoison_stack_memory' kernel/built-in.o: In function `perf_tp_event': (.text+0x22583a): undefined reference to `__asan_unpoison_stack_memory' kernel/built-in.o: In function `perf_tp_event': (.text+0x2258ae): undefined reference to `__asan_poison_stack_memory' kernel/built-in.o: In function `perf_event_aux_event': I think we really want to define those two functions so we can make use of a helpful feature, but as I have no idea what they are supposed to do, I'd suggest to turn the option off on existing kernels to allow building with gcc-7 and kasan. For some reason, the problem showed up in only a few randconfig builds, but it is easy to reproduce using an x86-64 tinyconfig build with CONFIG_KASAN=y. If we decide to take this approach, we probably want to do the same change on all stable kernels that support KASAN, i.e. v4.0 or higher. Link: https://gcc.gnu.org/viewcvs/gcc?limit_changes=0&view=revision&revision=241896 Cc: Martin Liška <marxin@xxxxxxxxxxx> Cc: Andrey Ryabinin <a.ryabinin@xxxxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx> --- scripts/Makefile.kasan | 2 ++ 1 file changed, 2 insertions(+) diff --git a/scripts/Makefile.kasan b/scripts/Makefile.kasan index 37323b0df374..0e68fef09f76 100644 --- a/scripts/Makefile.kasan +++ b/scripts/Makefile.kasan @@ -29,3 +29,5 @@ else endif endif endif + +CFLAGS_KASAN += $(call cc-option, -fno-sanitize-address-use-after-scope) -- 2.9.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
