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authorAndrey Konovalov <andreyknvl@google.com>2018-02-06 15:36:00 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2018-02-06 18:32:42 -0800
commit0e410e158e5baa1300bdf678cea4f4e0cf9d8b94 (patch)
treee857ad4dd093bff753dbecb2a4815a3ae84d0812
parente237f98a9c134c3d600353f21e07db915516875b (diff)
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kasan: don't emit builtin calls when sanitization is off
With KASAN enabled the kernel has two different memset() functions, one with KASAN checks (memset) and one without (__memset). KASAN uses some macro tricks to use the proper version where required. For example memset() calls in mm/slub.c are without KASAN checks, since they operate on poisoned slab object metadata. The issue is that clang emits memset() calls even when there is no memset() in the source code. They get linked with improper memset() implementation and the kernel fails to boot due to a huge amount of KASAN reports during early boot stages. The solution is to add -fno-builtin flag for files with KASAN_SANITIZE := n marker. Link: http://lkml.kernel.org/r/8ffecfffe04088c52c42b92739c2bd8a0bcb3f5e.1516384594.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Acked-by: Nick Desaulniers <ndesaulniers@google.com> Cc: Masahiro Yamada <yamada.masahiro@socionext.com> Cc: Michal Marek <michal.lkml@markovi.net> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Alexander Potapenko <glider@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--Makefile3
-rw-r--r--scripts/Makefile.kasan3
-rw-r--r--scripts/Makefile.lib2
3 files changed, 6 insertions, 2 deletions
diff --git a/Makefile b/Makefile
index 11aff0f9e105..0d49ff4022fb 100644
--- a/Makefile
+++ b/Makefile
@@ -434,7 +434,8 @@ export MAKE LEX YACC AWK GENKSYMS INSTALLKERNEL PERL PYTHON UTS_MACHINE
export HOSTCXX HOSTCXXFLAGS LDFLAGS_MODULE CHECK CHECKFLAGS
export KBUILD_CPPFLAGS NOSTDINC_FLAGS LINUXINCLUDE OBJCOPYFLAGS LDFLAGS
-export KBUILD_CFLAGS CFLAGS_KERNEL CFLAGS_MODULE CFLAGS_KASAN CFLAGS_UBSAN
+export KBUILD_CFLAGS CFLAGS_KERNEL CFLAGS_MODULE
+export CFLAGS_KASAN CFLAGS_KASAN_NOSANITIZE CFLAGS_UBSAN
export KBUILD_AFLAGS AFLAGS_KERNEL AFLAGS_MODULE
export KBUILD_AFLAGS_MODULE KBUILD_CFLAGS_MODULE KBUILD_LDFLAGS_MODULE
export KBUILD_AFLAGS_KERNEL KBUILD_CFLAGS_KERNEL
diff --git a/scripts/Makefile.kasan b/scripts/Makefile.kasan
index 1ce7115aa499..94c9e65cc83a 100644
--- a/scripts/Makefile.kasan
+++ b/scripts/Makefile.kasan
@@ -31,4 +31,7 @@ else
endif
CFLAGS_KASAN += $(call cc-option, -fsanitize-address-use-after-scope)
+
+CFLAGS_KASAN_NOSANITIZE := -fno-builtin
+
endif
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 5fdc1a19b02c..5589bae34af6 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -121,7 +121,7 @@ endif
ifeq ($(CONFIG_KASAN),y)
_c_flags += $(if $(patsubst n%,, \
$(KASAN_SANITIZE_$(basetarget).o)$(KASAN_SANITIZE)y), \
- $(CFLAGS_KASAN))
+ $(CFLAGS_KASAN), $(CFLAGS_KASAN_NOSANITIZE))
endif
ifeq ($(CONFIG_UBSAN),y)