[PATCH v2 18/33] lib/string: Add KMSAN support to strlcpy() and strlcat()

[Ilya Leoshkevich]

Currently KMSAN does not fully propagate metadata in strlcpy() and
strlcat(), because they are built with -ffreestanding and call
memcpy(). In this combination memcpy() calls are not instrumented.

Fix by copying the metadata manually. Add the __STDC_HOSTED__ #ifdef in
case the code is compiled with different flags in the future.

Signed-off-by: Ilya Leoshkevich <iii@xxxxxxxxxxxxx>
---
 lib/string.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/lib/string.c b/lib/string.c
index be26623953d2..e83c6dd77ec6 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -111,6 +111,9 @@ size_t strlcpy(char *dest, const char *src, size_t size)
 	if (size) {
 		size_t len = (ret >= size) ? size - 1 : ret;
 		__builtin_memcpy(dest, src, len);
+#if __STDC_HOSTED__ == 0
+		kmsan_memmove_metadata(dest, src, len);
+#endif
 		dest[len] = '\0';
 	}
 	return ret;
@@ -261,6 +264,9 @@ size_t strlcat(char *dest, const char *src, size_t count)
 	if (len >= count)
 		len = count-1;
 	__builtin_memcpy(dest, src, len);
+#if __STDC_HOSTED__ == 0
+	kmsan_memmove_metadata(dest, src, len);
+#endif
 	dest[len] = 0;
 	return res;
 }
-- 
2.41.0