[PATCH 1/5] kmsan: core: kmsan_in_runtime() should return true in NMI context

Alexander Potapenko
2022-11-02T11:06:20Z

Without that, every call to __msan_poison_alloca() in NMI may end up
allocating memory, which is NMI-unsafe.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/lkml/20221025221755.3810809-1-glider@google.com/
Signed-off-by: Alexander Potapenko <glider@google.com>
---
mm/kmsan/kmsan.h | 2 ++
1 file changed, 2 insertions(+)

diff --git a/mm/kmsan/kmsan.h b/mm/kmsan/kmsan.h
index 961eb658020aa..3cd2050a33e6a 100644
--- a/mm/kmsan/kmsan.h
+++ b/mm/kmsan/kmsan.h
@@ -125,6 +125,8 @@ static __always_inline bool kmsan_in_runtime(void)
{
if ((hardirq_count() >> HARDIRQ_SHIFT) > 1)
return true;
+ if (in_nmi())
+ return true;
return kmsan_get_context()->kmsan_in_runtime;
}

--
2.38.1.273.g43a17bfeac-goog