[PATCH 1/2] ubsan: allow to disable the null sanitizer

Christian Borntraeger
2016-09-12T12:37:19Z

Some architectures use a hardware defined struct at address zero.
Checking for a null pointer will result in many ubsan reports.
Let users disable the null sanitizer.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
---
lib/Kconfig.ubsan | 11 +++++++++++
scripts/Makefile.ubsan | 5 ++++-
2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/lib/Kconfig.ubsan b/lib/Kconfig.ubsan
index 39494af..851c3f2 100644
--- a/lib/Kconfig.ubsan
+++ b/lib/Kconfig.ubsan
@@ -1,6 +1,9 @@
config ARCH_HAS_UBSAN_SANITIZE_ALL
bool

+config ARCH_WANTS_UBSAN_NO_NULL
+ def_bool n
+
config UBSAN
bool "Undefined behaviour sanity checker"
help
@@ -34,3 +37,11 @@ config UBSAN_ALIGNMENT
This option enables detection of unaligned memory accesses.
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 UBSAN && !ARCH_WANTS_UBSAN_NO_NULL
+ help
+ This option enables detection of memory accesses via a
+ null pointer.
diff --git a/scripts/Makefile.ubsan b/scripts/Makefile.ubsan
index 77ce538..3b1b138 100644
--- a/scripts/Makefile.ubsan
+++ b/scripts/Makefile.ubsan
@@ -3,7 +3,6 @@ ifdef CONFIG_UBSAN
CFLAGS_UBSAN += $(call cc-option, -fsanitize=integer-divide-by-zero)
CFLAGS_UBSAN += $(call cc-option, -fsanitize=unreachable)
CFLAGS_UBSAN += $(call cc-option, -fsanitize=vla-bound)
- CFLAGS_UBSAN += $(call cc-option, -fsanitize=null)
CFLAGS_UBSAN += $(call cc-option, -fsanitize=signed-integer-overflow)
CFLAGS_UBSAN += $(call cc-option, -fsanitize=bounds)
CFLAGS_UBSAN += $(call cc-option, -fsanitize=object-size)
@@ -15,6 +14,10 @@ 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)
--
2.5.5