net: lwm2m: senml_cbor: Verify data len before calling memcpy

Check if there actually is data to copy before calling memcpy() to
prevent potentially calling memcpy() with NULL value pointer.

Signed-off-by: Robert Lubos <[email protected]>

Author: rlubos

subsys/net/lib/lwm2m/lwm2m_rw_senml_cbor.c

@@ -644,8 +644,9 @@ static int get_string(struct lwm2m_input_context *in, uint8_t *buf, size_t bufle
 	}
 
 	len = MIN(buflen-1, fd->current->record_union.union_vs.len);
-
-	memcpy(buf, fd->current->record_union.union_vs.value, len);
+	if (len > 0) {
+		memcpy(buf, fd->current->record_union.union_vs.value, len);
+	}
 	buf[len] = '\0';
 
 	fd->current = NULL;