[LU-6878] Potential NULL pointer dereference in top_trans_stop

• Type: Bug
• Resolution: Not a Bug
• Priority: Minor
• Severity: 3
• Assignee: Di Wang
• Reporter: Oleg Drokin

Description

top_trans_stop has this code:

                rc = dt_trans_stop(env, master_st->st_dt, master_st->st_sub_th);
                if (rc < 0) {
                        th->th_result = rc;
                        GOTO(stop_other_trans, rc);
                } else if (tur != NULL && tur->tur_update_records != NULL) {
                        struct llog_update_record *lur;

                        lur = tur->tur_update_records;
....
        if (write_updates) {
                struct llog_update_record *lur;

                /* Stop callback of master will add more updates and also update
                 * master transno, so merge the parameters and updates into one
                 * buffer again */
                rc = prepare_writing_updates(env, tmt);
                if (rc < 0) {
                        CERROR("%s: prepare updates failed: rc = %d\n",
                               master_dev->dd_lu_dev.ld_obd->obd_name, rc);
                        th->th_result = rc;
                        GOTO(stop_other_trans, rc);
                }
                lur = tur->tur_update_records;

So in a very similar bits one makes sure tur is not NULL and the other takes it for granted which is a bit strange and probably hides a bug.