scsi: iscsi: Fix race condition between login and sync thread

A kernel panic was observed due to a timing issue between the sync thread
and the initiator processing a login response from the target. The session
reopen can be invoked both from the session sync thread when iscsid
restarts and from iscsid through the error handler. Before the initiator
receives the response to a login, another reopen request can be sent from
the error handler/sync session. When the initial login response is
subsequently processed, the connection has been closed and the socket has
been released.

To fix this a new connection state, ISCSI_CONN_BOUND, is added:

 - Set the connection state value to ISCSI_CONN_DOWN upon
   iscsi_if_ep_disconnect() and iscsi_if_stop_conn()

 - Set the connection state to the newly created value ISCSI_CONN_BOUND
   after bind connection (transport->bind_conn())

 - In iscsi_set_param(), return -ENOTCONN if the connection state is not
   either ISCSI_CONN_BOUND or ISCSI_CONN_UP

Link: https://lore.kernel.org/r/20210325093248.284678-1-gulam.mohamed@oracle.com
Reviewed-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Gulam Mohamed <gulam.mohamed@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
index 91074fd97f64..f4bf62b007a0 100644

diff --git a/drivers/scsi/scsi_transport_iscsi.c b/drivers/scsi/scsi_transport_iscsi.c
index 969d24d580e29b46a23d4df097bd19121e837c18..bebfb355abdf74ffe7190f5e15ff790a8cf36d6a 100644 (file)
--- a/drivers/scsi/scsi_transport_iscsi.c
+++ b/drivers/scsi/scsi_transport_iscsi.c
@@ -2471,6 +2471,7 @@ static void iscsi_if_stop_conn(struct iscsi_cls_conn *conn, int flag)
         */
        mutex_lock(&conn_mutex);
        conn->transport->stop_conn(conn, flag);
+       conn->state = ISCSI_CONN_DOWN;
        mutex_unlock(&conn_mutex);
 
 }
@@ -2894,6 +2895,13 @@ iscsi_set_param(struct iscsi_transport *transport, struct iscsi_uevent *ev)
        default:
                err = transport->set_param(conn, ev->u.set_param.param,
                                           data, ev->u.set_param.len);
+               if ((conn->state == ISCSI_CONN_BOUND) ||
+                       (conn->state == ISCSI_CONN_UP)) {
+                       err = transport->set_param(conn, ev->u.set_param.param,
+                                       data, ev->u.set_param.len);
+               } else {
+                       return -ENOTCONN;
+               }
        }
 
        return err;
@@ -2953,6 +2961,7 @@ static int iscsi_if_ep_disconnect(struct iscsi_transport *transport,
                mutex_lock(&conn->ep_mutex);
                conn->ep = NULL;
                mutex_unlock(&conn->ep_mutex);
+               conn->state = ISCSI_CONN_DOWN;
        }
 
        transport->ep_disconnect(ep);
@@ -3713,6 +3722,8 @@ iscsi_if_recv_msg(struct sk_buff *skb, struct nlmsghdr *nlh, uint32_t *group)
                ev->r.retcode = transport->bind_conn(session, conn,
                                                ev->u.b_conn.transport_eph,
                                                ev->u.b_conn.is_leading);
+               if (!ev->r.retcode)
+                       conn->state = ISCSI_CONN_BOUND;
                mutex_unlock(&conn_mutex);
 
                if (ev->r.retcode || !transport->ep_connect)
@@ -3944,7 +3955,8 @@ iscsi_conn_attr(local_ipaddr, ISCSI_PARAM_LOCAL_IPADDR);
 static const char *const connection_state_names[] = {
        [ISCSI_CONN_UP] = "up",
        [ISCSI_CONN_DOWN] = "down",
-       [ISCSI_CONN_FAILED] = "failed"
+       [ISCSI_CONN_FAILED] = "failed",
+       [ISCSI_CONN_BOUND] = "bound"
 };
 
 static ssize_t show_conn_state(struct device *dev,

diff --git a/include/scsi/scsi_transport_iscsi.h b/include/scsi/scsi_transport_iscsi.h
index 8a26a2ffa95234e9ce1a31492af236f774f71244..fc5a39839b4b02cc32642379f5eeeee662020af9 100644 (file)
--- a/include/scsi/scsi_transport_iscsi.h
+++ b/include/scsi/scsi_transport_iscsi.h
@@ -193,6 +193,7 @@ enum iscsi_connection_state {
        ISCSI_CONN_UP = 0,
        ISCSI_CONN_DOWN,
        ISCSI_CONN_FAILED,
+       ISCSI_CONN_BOUND,
 };
 
 struct iscsi_cls_conn {