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: 56bc3b2094b4 ("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>

1 files changed, 5 insertions, 3 deletions

diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
index 1c9289f56dc4..211cd91b6c40 100644
--- 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. */