To avoid false positives, assume that reading from the task stack
always produces initialized values.
Signed-off-by: Alexander Potapenko <glider@xxxxxxxxxx>
To: Alexander Potapenko <glider@xxxxxxxxxx>
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
Acked-by: Marco Elver <elver@xxxxxxxxxx>
---
v4:
- added an #include as requested by Marco Elver
Change-Id: Ie73e5a41fdc8195699928e65f5cbe0d3d3c9e2fa
---
arch/x86/include/asm/unwind.h | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/arch/x86/include/asm/unwind.h b/arch/x86/include/asm/unwind.h
index 499578f7e6d7b..82c3bceb9999c 100644
--- a/arch/x86/include/asm/unwind.h
+++ b/arch/x86/include/asm/unwind.h
@@ -4,6 +4,7 @@
#include <linux/sched.h>
#include <linux/ftrace.h>
+#include <linux/kmsan-checks.h>
#include <asm/ptrace.h>
#include <asm/stacktrace.h>
@@ -100,9 +101,10 @@ void unwind_module_init(struct module *mod, void *orc_ip, size_t orc_ip_size,
#endif
/*
- * This disables KASAN checking when reading a value from another task's stack,
- * since the other task could be running on another CPU and could have poisoned
- * the stack in the meantime.
+ * This disables KASAN/KMSAN checking when reading a value from another task's
+ * stack, since the other task could be running on another CPU and could have
+ * poisoned the stack in the meantime. Frame pointers are uninitialized by
+ * default, so for KMSAN we mark the return value initialized unconditionally.
*/
#define READ_ONCE_TASK_STACK(task, x) \
({ \
@@ -111,7 +113,7 @@ void unwind_module_init(struct module *mod, void *orc_ip, size_t orc_ip_size,
val = READ_ONCE(x); \
else \
val = READ_ONCE_NOCHECK(x); \
- val; \
+ KMSAN_INIT_VALUE(val); \
})
static inline bool task_on_another_cpu(struct task_struct *task)
--
2.25.1.696.g5e7596f4ac-goog
