Merge pull request #5180 from sysown/v3.0-fix_use_after_free_in_proclist

Fix potential 'use-after-free' by Admin 'SHOW PROCESSLIST'

lib/MySQL_Session.cpp

@@ -8126,8 +8126,8 @@ char* MySQL_Session::get_current_query(int max_length) {
 	}
 
 	if (CurrentQuery.stmt_info == NULL) { // text protocol
-		query_ptr = mybe->server_myds->myconn->query.ptr;
-		query_len = mybe->server_myds->myconn->query.length;
+		query_ptr = reinterpret_cast<const char*>(CurrentQuery.QueryPointer);
+		query_len = CurrentQuery.QueryLength;
 	} else { // prepared statement
 		query_ptr = CurrentQuery.stmt_info->query;
 		query_len = CurrentQuery.stmt_info->query_length;
@@ -8145,8 +8145,8 @@ char* MySQL_Session::get_current_query(int max_length) {
 		res = (char *) malloc(query_len + 1);
 		if (trunc_query) {
 			// for truncated queries, add three dots at the end
-			strncpy(res, query_ptr, query_len - 3);
-			strncpy(res + (query_len - 3), "...", 3);
+			memcpy(res, query_ptr, query_len - 3);
+			memcpy(res + (query_len - 3), "...", 3);
 		} else {
 			strncpy(res, query_ptr, query_len);
 		}
@@ -8154,4 +8154,4 @@ char* MySQL_Session::get_current_query(int max_length) {
 	}
 
 	return res;
-}
+}