On Fri, Oct 02, 2020 at 03:15:26PM -0700, Kees Cook wrote: > Clang handles 'maybe-uninitialized' better in the face of using UBSAN, > so do not make this universally disabled for UBSAN builds. > > Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> Well this patch is not strictly necessary because Clang does not support -Wmaybe-uninitialized anyways :) its flags are -Wuninitialized and -Wsometimes-uninitialized so the warning stays enabled for UBSAN as it stands. However, something like this could still worthwhile because it would save us one call to cc-disable-warning (yay micro optimizations). Maybe it just does not need to have a whole new symbol, just make it ubsan-cflags-$(CONFIG_CC_IS_GCC) instead of ubsan-cflags-$(CONFIG_UBSAN) No strong opinions either way though. > --- > lib/Kconfig.ubsan | 6 ++++++ > scripts/Makefile.ubsan | 6 +++--- > 2 files changed, 9 insertions(+), 3 deletions(-) > > diff --git a/lib/Kconfig.ubsan b/lib/Kconfig.ubsan > index aeb2cdea0b94..1fc07f936e06 100644 > --- a/lib/Kconfig.ubsan > +++ b/lib/Kconfig.ubsan > @@ -36,6 +36,12 @@ config UBSAN_KCOV_BROKEN > See https://bugs.llvm.org/show_bug.cgi?id=45831 for the status > in newer releases. > > +config UBSAN_DISABLE_MAYBE_UNINITIALIZED > + def_bool CC_IS_GCC > + help > + -fsanitize=* options makes GCC less smart than usual and > + increases the number of 'maybe-uninitialized' false-positives. > + > config CC_HAS_UBSAN_BOUNDS > def_bool $(cc-option,-fsanitize=bounds) > > diff --git a/scripts/Makefile.ubsan b/scripts/Makefile.ubsan > index 72862da47baf..c5ef6bac09d4 100644 > --- a/scripts/Makefile.ubsan > +++ b/scripts/Makefile.ubsan > @@ -1,8 +1,8 @@ > # SPDX-License-Identifier: GPL-2.0 > > -# -fsanitize=* options makes GCC less smart than usual and > -# increases the number of 'maybe-uninitialized' false-positives. > -ubsan-cflags-$(CONFIG_UBSAN) += $(call cc-disable-warning, maybe-uninitialized) > +# The "maybe-uninitialized" warning can be very noisy. > +ubsan-cflags-$(CONFIG_UBSAN_DISABLE_MAYBE_UNINITIALIZED) += \ > + $(call cc-disable-warning, maybe-uninitialized) > > # Enable available and selected UBSAN features. > ubsan-cflags-$(CONFIG_UBSAN_ALIGNMENT) += -fsanitize=alignment > -- > 2.25.1
