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

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Date:   Wed,  2 Nov 2022 12:06:07 +0100
From:   Alexander Potapenko <glider@...gle.com>
To:     glider@...gle.com
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Marco Elver <elver@...gle.com>,
        Peter Zijlstra <peterz@...radead.org>
Subject: [PATCH 1/5] kmsan: core: kmsan_in_runtime() should return true in NMI context

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

Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Dmitry Vyukov <dvyukov@...gle.com>
Cc: Marco Elver <elver@...gle.com>
Cc: Peter Zijlstra (Intel) <peterz@...radead.org>
Link: https://lore.kernel.org/lkml/20221025221755.3810809-1-glider@google.com/
Signed-off-by: Alexander Potapenko <glider@...gle.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