[PATCH RFC v2 24/25] kmsan: disable strscpy() optimization under KMSAN

[glider@google.com]

Disable the efficient 8-byte reading under KMSAN to avoid false positives.

Signed-off-by: Alexander Potapenko <glider@google.com>
To: Alexander Potapenko <glider@google.com>
Cc: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: linux-mm@kvack.org

---

Change-Id: I25d1acf5c3df6eff85894cd94f5ddbe93308271c
---
 lib/string.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/lib/string.c b/lib/string.c
index 08ec58cc673b..15efdc51bda6 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -186,7 +186,10 @@ ssize_t strscpy(char *dest, const char *src, size_t count)
 	if (count == 0 || WARN_ON_ONCE(count > INT_MAX))
 		return -E2BIG;
 
-#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
+/**
+ * Disable the efficient 8-byte reading under KMSAN to avoid false positives.
+ */
+#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && !defined(CONFIG_KMSAN)
 	/*
 	 * If src is unaligned, don't cross a page boundary,
 	 * since we don't know if the next page is mapped.
-- 
2.24.0.rc0.303.g954a862665-goog