On 7/22/19 12:10 PM, Arnd Bergmann wrote:
objtool points out several conditions that it does not like, depending on the combination with other configuration options and compiler variants:
stack protector: lib/ubsan.o: warning: objtool: __ubsan_handle_type_mismatch()+0xbf: call to __stack_chk_fail() with UACCESS enabled lib/ubsan.o: warning: objtool: __ubsan_handle_type_mismatch_v1()+0xbe: call to __stack_chk_fail() with UACCESS enabled
stackleak plugin: lib/ubsan.o: warning: objtool: __ubsan_handle_type_mismatch()+0x4a: call to stackleak_track_stack() with UACCESS enabled lib/ubsan.o: warning: objtool: __ubsan_handle_type_mismatch_v1()+0x4a: call to stackleak_track_stack() with UACCESS enabled
kasan: lib/ubsan.o: warning: objtool: __ubsan_handle_type_mismatch()+0x25: call to memcpy() with UACCESS enabled lib/ubsan.o: warning: objtool: __ubsan_handle_type_mismatch_v1()+0x25: call to memcpy() with UACCESS enabled
The stackleak and kasan options just need to be disabled for this file as we do for other files already. For the stack protector, we already attempt to disable it, but this fails on clang because the check is mixed with the gcc specific -fno-conserve-stack option, so we need to test them separately.
Fixes: 42440c1f9911 ("lib/ubsan: add type mismatch handler for new GCC/Clang")
There was no uaccess validataion at that time, so the right fixes line is probably this:
Fixes: d08965a27e84 ("x86/uaccess, ubsan: Fix UBSAN vs. SMAP")
Link: https://lore.kernel.org/lkml/20190617123109.667090-1-arnd@arndb.de/t/ Cc: stable@vger.kernel.org Signed-off-by: Arnd Bergmann arnd@arndb.de
lib/Makefile | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/lib/Makefile b/lib/Makefile index 095601ce371d..320e3b632dd3 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -279,7 +279,8 @@ obj-$(CONFIG_UCS2_STRING) += ucs2_string.o obj-$(CONFIG_UBSAN) += ubsan.o UBSAN_SANITIZE_ubsan.o := n -CFLAGS_ubsan.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) +KASAN_SANITIZE_ubsan.o := n +CFLAGS_ubsan.o := $(call cc-option, -fno-conserve-stack) $(call cc-option, -fno-stack-protector) $(DISABLE_STACKLEAK_PLUGIN)
$(call cc-option, -fno-conserve-stack) can be removed entirely. It's just copy paste from kasan Makefile. It was added in kasan purely for performance reasons.
Not sure that it's needed even in kasan Makefile, the code which was the reason for adding fno-conserve-stack might not get into the final version of KASAN patches.