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    Subject[PATCH 5.15 323/846] net/smc: Reset conn->lgr when link group registration fails
    Date
    From: Wen Gu <guwen@linux.alibaba.com>

    [ 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@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>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    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


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