From cbadaf71f7cf9e67c073eec673c6c050cecd0ec8 Mon Sep 17 00:00:00 2001
From: Alexander Potapenko <glider@google.com>
Date: Wed, 2 Nov 2022 12:06:07 +0100
Subject: [PATCH] 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.

Link: https://lkml.kernel.org/r/20221102110611.1085175-1-glider@google.com
Link: https://lore.kernel.org/lkml/20221025221755.3810809-1-glider@google.com/
Signed-off-by: Alexander Potapenko <glider@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 mm/kmsan/kmsan.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/mm/kmsan/kmsan.h b/mm/kmsan/kmsan.h
index 7019c46d33a7..a14744205435 100644
--- a/mm/kmsan/kmsan.h
+++ b/mm/kmsan/kmsan.h
@@ -124,6 +124,8 @@ 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;
 }