The patch titled
Subject: kasan: don't emit builtin calls when sanitization is off
has been added to the -mm tree. Its filename is
kasan-dont-emit-builtin-calls-when-sanitization-is-off.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/kasan-dont-emit-builtin-calls-when-sanitization-is-off.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/kasan-dont-emit-builtin-calls-when-sanitization-is-off.patch
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------------------------------------------------------
From: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Subject: 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@xxxxxxxxxx
Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Acked-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
Cc: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>
Cc: Michal Marek <michal.lkml@xxxxxxxxxxx>
Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Makefile | 3 ++-
scripts/Makefile.kasan | 3 +++
scripts/Makefile.lib | 2 +-
3 files changed, 6 insertions(+), 2 deletions(-)
diff -puN Makefile~kasan-dont-emit-builtin-calls-when-sanitization-is-off Makefile
--- a/Makefile~kasan-dont-emit-builtin-calls-when-sanitization-is-off
+++ a/Makefile
@@ -432,7 +432,8 @@ export MAKE AWK GENKSYMS INSTALLKERNEL P
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 -puN scripts/Makefile.kasan~kasan-dont-emit-builtin-calls-when-sanitization-is-off scripts/Makefile.kasan
--- a/scripts/Makefile.kasan~kasan-dont-emit-builtin-calls-when-sanitization-is-off
+++ a/scripts/Makefile.kasan
@@ -31,4 +31,7 @@ else
endif
CFLAGS_KASAN += $(call cc-option, -fsanitize-address-use-after-scope)
+
+CFLAGS_KASAN_NOSANITIZE := -fno-builtin
+
endif
diff -puN scripts/Makefile.lib~kasan-dont-emit-builtin-calls-when-sanitization-is-off scripts/Makefile.lib
--- a/scripts/Makefile.lib~kasan-dont-emit-builtin-calls-when-sanitization-is-off
+++ a/scripts/Makefile.lib
@@ -121,7 +121,7 @@ endif
ifeq ($(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)
_
Patches currently in -mm which might be from andreyknvl@xxxxxxxxxx are
kasan-dont-emit-builtin-calls-when-sanitization-is-off.patch
kasan-fix-prototype-author-email-address.patch
kasan-clean-up-kasan_shadow_scale_shift-usage.patch