From 3ca17b1f3628f916f79e0ab62f1bf0e45ec9ba92 Mon Sep 17 00:00:00 2001
From: Andrey Ryabinin <aryabinin@virtuozzo.com>
Date: Fri, 10 Aug 2018 17:23:03 -0700
Subject: [PATCH] lib/ubsan: remove null-pointer checks
With gcc-8 fsanitize=null become very noisy. GCC started to complain
about things like &a->b, where 'a' is NULL pointer. There is no NULL
dereference, we just calculate address to struct member. It's
technically undefined behavior so UBSAN is correct to report it. But as
long as there is no real NULL-dereference, I think, we should be fine.
-fno-delete-null-pointer-checks compiler flag should protect us from any
consequences. So let's just no use -fsanitize=null as it's not useful
for us. If there is a real NULL-deref we will see crash. Even if
userspace mapped something at NULL (root can do this), with things like
SMAP should catch the issue.
Link: http://lkml.kernel.org/r/20180802153209.813-1-aryabinin@virtuozzo.com
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
arch/parisc/Kconfig | 1 -
arch/s390/Kconfig | 1 -
lib/Kconfig.ubsan | 11 -----------
scripts/Makefile.ubsan | 4 ----
4 files changed, 17 deletions(-)
diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig
index 46f656b8fc233..e7705dde953fc 100644
--- a/arch/parisc/Kconfig
+++ b/arch/parisc/Kconfig
@@ -11,7 +11,6 @@ config PARISC
select ARCH_HAS_ELF_RANDOMIZE
select ARCH_HAS_STRICT_KERNEL_RWX
select ARCH_HAS_UBSAN_SANITIZE_ALL
- select ARCH_WANTS_UBSAN_NO_NULL
select ARCH_SUPPORTS_MEMORY_FAILURE
select RTC_CLASS
select RTC_DRV_GENERIC
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 8a1863d9ed533..4fe5b2affa233 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -106,7 +106,6 @@ config S390
select ARCH_USE_BUILTIN_BSWAP
select ARCH_USE_CMPXCHG_LOCKREF
select ARCH_WANTS_DYNAMIC_TASK_STRUCT
- select ARCH_WANTS_UBSAN_NO_NULL
select ARCH_WANT_IPC_PARSE_VERSION
select BUILDTIME_EXTABLE_SORT
select CLONE_BACKWARDS2
diff --git a/lib/Kconfig.ubsan b/lib/Kconfig.ubsan
index 19d42ea75ec22..98fa559ebd808 100644
--- a/lib/Kconfig.ubsan
+++ b/lib/Kconfig.ubsan
@@ -1,9 +1,6 @@
config ARCH_HAS_UBSAN_SANITIZE_ALL
bool
-config ARCH_WANTS_UBSAN_NO_NULL
- def_bool n
-
config UBSAN
bool "Undefined behaviour sanity checker"
help
@@ -39,14 +36,6 @@ config UBSAN_ALIGNMENT
Enabling this option on architectures that support unaligned
accesses may produce a lot of false positives.
-config UBSAN_NULL
- bool "Enable checking of null pointers"
- depends on UBSAN
- default y if !ARCH_WANTS_UBSAN_NO_NULL
- help
- This option enables detection of memory accesses via a
- null pointer.
-
config TEST_UBSAN
tristate "Module for testing for undefined behavior detection"
depends on m && UBSAN
diff --git a/scripts/Makefile.ubsan b/scripts/Makefile.ubsan
index b593b36ccff86..38b2b4818e8eb 100644
--- a/scripts/Makefile.ubsan
+++ b/scripts/Makefile.ubsan
@@ -14,10 +14,6 @@ ifdef CONFIG_UBSAN_ALIGNMENT
CFLAGS_UBSAN += $(call cc-option, -fsanitize=alignment)
endif
-ifdef CONFIG_UBSAN_NULL
- CFLAGS_UBSAN += $(call cc-option, -fsanitize=null)
-endif
-
# -fsanitize=* options makes GCC less smart than usual and
# increase number of 'maybe-uninitialized false-positives
CFLAGS_UBSAN += $(call cc-option, -Wno-maybe-uninitialized)
--
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