On 02/04/2015 10:24 PM, kbuild test robot wrote: > tree: git://git.cmpxchg.org/linux-mmotm.git master > head: f03806f9a6908743ed1902389be1a4a6198852be > commit: 7bc18a57df7c27948b9d93fa4eefc20e3e200512 [409/551] kasan: enable instrumentation of global variables > config: x86_64-allmodconfig (attached as .config) > reproduce: > git checkout 7bc18a57df7c27948b9d93fa4eefc20e3e200512 > # save the attached .config to linux build tree > make ARCH=x86_64 > > All warnings: > >>> WARNING: arch/x86/kernel/cpu/microcode/microcode.o(.data+0x1cf0): Section mismatch in reference from the variable microcode_mutex to the variable .init.rodata:__mod_x86cpu__microcode_id_device_table > The variable microcode_mutex references > the variable __initconst __mod_x86cpu__microcode_id_device_table Obviously 'microcode_mutex' doesn't reference '__mod_x86cpu__microcode_id_device_table'. Actually this is struct kasan_global describing '__mod_x86cpu__microcode_id_device_table' variable references it. Normally GCC doesn't instrument globals in user-specified sections. So we shouldn't have kasan_global struct for '__mod_x86cpu__microcode_id_device_table', because this symbol doesn't have redzone. '__mod_x86cpu__microcode_id_device_table' is an alias to 'microcode_id' symbol and alias declared without specifying section. It seems that GCC looks only on declaration, and it thinks that __mod_x86cpu__microcode_id_device_table is in default section. So we poison redzone for microcode_id symbol, which don't have redzone. IOW we poison some valid memory. This bug already fixed in trunk GCC, but it present in 4.9.2. I think the best option here is just disable globals instrumentation for 4.9.2. In addition to patch bellow, 'kernel-add-support-for-init_array-constructors.patch' patch could be dropped, as we needed it only for 4.9.2 GCC. ---- From: Andrey Ryabinin <a.ryabinin@xxxxxxxxxxx> Subject: kasan-enable-instrumentation-of-global-variables-fix-2 Disable broken globals instrumentation for GCC 4.9.2 Signed-off-by: Andrey Ryabinin <a.ryabinin@xxxxxxxxxxx> --- scripts/Makefile.kasan | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/scripts/Makefile.kasan b/scripts/Makefile.kasan index 72a40bb..631619b 100644 --- a/scripts/Makefile.kasan +++ b/scripts/Makefile.kasan @@ -5,7 +5,7 @@ else call_threshold := 0 endif -CFLAGS_KASAN_MINIMAL := -fsanitize=kernel-address --param asan-globals=1 +CFLAGS_KASAN_MINIMAL := -fsanitize=kernel-address CFLAGS_KASAN := $(call cc-option, -fsanitize=kernel-address \ -fasan-shadow-offset=$(CONFIG_KASAN_SHADOW_OFFSET) \ -- 2.2.2 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>