[PATCH 5.15 323/846] net/smc: Reset conn->lgr when link group registration fails

From: Greg Kroah-Hartman
Date: Mon Jan 24 2022 - 15:52:05 EST


From: Wen Gu <guwen@xxxxxxxxxxxxxxxxx>

[ Upstream commit 36595d8ad46d9e4c41cc7c48c4405b7c3322deac ]

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@xxxxxxxxxxxxx>
Signed-off-by: Wen Gu <guwen@xxxxxxxxxxxxxxxxx>
Acked-by: Karsten Graul <kgraul@xxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
net/smc/af_smc.c | 8 +++++---
net/smc/smc_core.c | 12 +++++++-----
net/smc/smc_core.h | 2 +-
3 files changed, 13 insertions(+), 9 deletions(-)

diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
index eea6d4a854e90..07ff719f39077 100644
--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c
@@ -613,10 +613,12 @@ 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 506b8498623b0..79d5e6a90845d 100644
--- a/net/smc/smc_core.c
+++ b/net/smc/smc_core.c
@@ -170,8 +170,10 @@ 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
@@ -579,15 +581,13 @@ 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 */
@@ -1750,8 +1750,10 @@ 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 51a3e8248ade2..9a0523f4c7ba6 100644
--- a/net/smc/smc_core.h
+++ b/net/smc/smc_core.h
@@ -419,7 +419,7 @@ 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);
--
2.34.1