net/smc: Reset conn->lgr when link group registration fails

SMC connections might fail to be registered in a link group due to
unable to find a usable link during its creation. As a result,
smc_conn_create() will return a failure and most resources related
to the connection won't be applied or initialized, such as
conn->abort_work or conn->lnk.

If smc_conn_free() is invoked later, it will try to access the
uninitialized resources related to the connection, thus causing
a warning or crash.

This patch tries to fix this by resetting conn->lgr to NULL if an
abnormal exit occurs in smc_lgr_register_conn(), thus avoiding the
access to uninitialized resources in smc_conn_free().

Meanwhile, the new created link group should be terminated if smc
connections can't be registered in it. So smc_lgr_cleanup_early() is
modified to take care of link group only and invoked to terminate
unusable link group by smc_conn_create(). The call to smc_conn_free()
is moved out from smc_lgr_cleanup_early() to smc_conn_abort().

Fixes: b3577aa1f940 ("net/smc: assign link to a new connection")
Suggested-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: Wen Gu <guwen@linux.alibaba.com>
Acked-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
index 1c9289f56dc471d33b08f6138bee3bea8aabe26f..211cd91b6c4085becf7a06318f7284a2ed844594 100644 (file)
--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c
@@ -632,10 +632,12 @@ static int smc_connect_decline_fallback(struct smc_sock *smc, int reason_code,
 
 static void smc_conn_abort(struct smc_sock *smc, int local_first)
 {
+       struct smc_connection *conn = &smc->conn;
+       struct smc_link_group *lgr = conn->lgr;
+
+       smc_conn_free(conn);
        if (local_first)
-               smc_lgr_cleanup_early(&smc->conn);
-       else
-               smc_conn_free(&smc->conn);
+               smc_lgr_cleanup_early(lgr);
 }
 
 /* check if there is a rdma device available for this connection. */

diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c
index a6849362f4ddd34200d1e37ab57cabe2e3c30259..c9a8092c4ac96023246ebcea062d9ee14a68ffe6 100644 (file)
--- a/net/smc/smc_core.c
+++ b/net/smc/smc_core.c
@@ -171,8 +171,10 @@ static int smc_lgr_register_conn(struct smc_connection *conn, bool first)
 
        if (!conn->lgr->is_smcd) {
                rc = smcr_lgr_conn_assign_link(conn, first);
-               if (rc)
+               if (rc) {
+                       conn->lgr = NULL;
                        return rc;
+               }
        }
        /* find a new alert_token_local value not yet used by some connection
         * in this link group
@@ -622,15 +624,13 @@ int smcd_nl_get_lgr(struct sk_buff *skb, struct netlink_callback *cb)
        return skb->len;
 }
 
-void smc_lgr_cleanup_early(struct smc_connection *conn)
+void smc_lgr_cleanup_early(struct smc_link_group *lgr)
 {
-       struct smc_link_group *lgr = conn->lgr;
        spinlock_t *lgr_lock;
 
        if (!lgr)
                return;
 
-       smc_conn_free(conn);
        smc_lgr_list_head(lgr, &lgr_lock);
        spin_lock_bh(lgr_lock);
        /* do not use this link group for new connections */
@@ -1832,8 +1832,10 @@ create:
                write_lock_bh(&lgr->conns_lock);
                rc = smc_lgr_register_conn(conn, true);
                write_unlock_bh(&lgr->conns_lock);
-               if (rc)
+               if (rc) {
+                       smc_lgr_cleanup_early(lgr);
                        goto out;
+               }
        }
        conn->local_tx_ctrl.common.type = SMC_CDC_MSG_TYPE;
        conn->local_tx_ctrl.len = SMC_WR_TX_SIZE;

diff --git a/net/smc/smc_core.h b/net/smc/smc_core.h
index d63b08274197eb28959f099c90548938baa6eefd..73d0c35d3eb77bb1843f2e5bb43c20fdc1e9defa 100644 (file)
--- a/net/smc/smc_core.h
+++ b/net/smc/smc_core.h
@@ -468,7 +468,7 @@ static inline void smc_set_pci_values(struct pci_dev *pci_dev,
 struct smc_sock;
 struct smc_clc_msg_accept_confirm;
 
-void smc_lgr_cleanup_early(struct smc_connection *conn);
+void smc_lgr_cleanup_early(struct smc_link_group *lgr);
 void smc_lgr_terminate_sched(struct smc_link_group *lgr);
 void smcr_port_add(struct smc_ib_device *smcibdev, u8 ibport);
 void smcr_port_err(struct smc_ib_device *smcibdev, u8 ibport);