READ_ONCE_NOCHECK() is already used by KASAN to ignore memory accesses
from e.g. stack unwinders.
Define READ_ONCE_NOCHECK() for KMSAN so that it returns initialized
values. This helps defeat false positives from leftover stack contents.
Signed-off-by: Alexander Potapenko <glider@xxxxxxxxxx>
To: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Vegard Nossum <vegard.nossum@xxxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Marco Elver <elver@xxxxxxxxxx>
Cc: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Cc: linux-mm@xxxxxxxxx
---
v3:
- removed unnecessary #ifdef as requested by Mark Rutland
v4:
- added an #include as requested by Marco Elver
Change-Id: Ib38369ba038ab3b581d8e45b81036c3304fb79cb
---
include/linux/compiler.h | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index f504edebd5d71..c6c67729729e3 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -279,6 +279,7 @@ void __write_once_size(volatile void *p, void *res, int size)
*/
#include <asm/barrier.h>
#include <linux/kasan-checks.h>
+#include <linux/kmsan-checks.h>
#define __READ_ONCE(x, check) \
({ \
@@ -294,9 +295,9 @@ void __write_once_size(volatile void *p, void *res, int size)
/*
* Use READ_ONCE_NOCHECK() instead of READ_ONCE() if you need
- * to hide memory access from KASAN.
+ * to hide memory access from KASAN or KMSAN.
*/
-#define READ_ONCE_NOCHECK(x) __READ_ONCE(x, 0)
+#define READ_ONCE_NOCHECK(x) KMSAN_INIT_VALUE(__READ_ONCE(x, 0))
static __no_kasan_or_inline
unsigned long read_word_at_a_time(const void *addr)
--
2.25.1.696.g5e7596f4ac-goog
