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    Subject[PATCH 4.4 70/87] iscsi-target: Make TASK_REASSIGN use proper se_cmd->cmd_kref
    Date
    4.4-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Nicholas Bellinger <nab@linux-iscsi.org>

    commit ae072726f6109bb1c94841d6fb3a82dde298ea85 upstream.

    Since commit 59b6986dbf fixed a potential NULL pointer dereference
    by allocating a se_tmr_req for ISCSI_TM_FUNC_TASK_REASSIGN, the
    se_tmr_req is currently leaked by iscsit_free_cmd() because no
    iscsi_cmd->se_cmd.se_tfo was associated.

    To address this, treat ISCSI_TM_FUNC_TASK_REASSIGN like any other
    TMR and call transport_init_se_cmd() + target_get_sess_cmd() to
    setup iscsi_cmd->se_cmd.se_tfo with se_cmd->cmd_kref of 2.

    This will ensure normal release operation once se_cmd->cmd_kref
    reaches zero and target_release_cmd_kref() is invoked, se_tmr_req
    will be released via existing target_free_cmd_mem() and
    core_tmr_release_req() code.

    Reported-by: Donald White <dew@datera.io>
    Cc: Donald White <dew@datera.io>
    Cc: Mike Christie <mchristi@redhat.com>
    Cc: Hannes Reinecke <hare@suse.com>
    Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>



    ---
    drivers/target/iscsi/iscsi_target.c | 20 +++++++-------------
    1 file changed, 7 insertions(+), 13 deletions(-)

    --- a/drivers/target/iscsi/iscsi_target.c
    +++ b/drivers/target/iscsi/iscsi_target.c
    @@ -1759,7 +1759,6 @@ iscsit_handle_task_mgt_cmd(struct iscsi_
    struct iscsi_tmr_req *tmr_req;
    struct iscsi_tm *hdr;
    int out_of_order_cmdsn = 0, ret;
    - bool sess_ref = false;
    u8 function, tcm_function = TMR_UNKNOWN;

    hdr = (struct iscsi_tm *) buf;
    @@ -1801,18 +1800,17 @@ iscsit_handle_task_mgt_cmd(struct iscsi_
    buf);
    }

    + transport_init_se_cmd(&cmd->se_cmd, &iscsi_ops,
    + conn->sess->se_sess, 0, DMA_NONE,
    + TCM_SIMPLE_TAG, cmd->sense_buffer + 2);
    +
    + target_get_sess_cmd(&cmd->se_cmd, true);
    +
    /*
    * TASK_REASSIGN for ERL=2 / connection stays inside of
    * LIO-Target $FABRIC_MOD
    */
    if (function != ISCSI_TM_FUNC_TASK_REASSIGN) {
    - transport_init_se_cmd(&cmd->se_cmd, &iscsi_ops,
    - conn->sess->se_sess, 0, DMA_NONE,
    - TCM_SIMPLE_TAG, cmd->sense_buffer + 2);
    -
    - target_get_sess_cmd(&cmd->se_cmd, true);
    - sess_ref = true;
    -
    switch (function) {
    case ISCSI_TM_FUNC_ABORT_TASK:
    tcm_function = TMR_ABORT_TASK;
    @@ -1951,12 +1949,8 @@ attach:
    * For connection recovery, this is also the default action for
    * TMR TASK_REASSIGN.
    */
    - if (sess_ref) {
    - pr_debug("Handle TMR, using sess_ref=true check\n");
    - target_put_sess_cmd(&cmd->se_cmd);
    - }
    -
    iscsit_add_cmd_to_response_queue(cmd, conn, cmd->i_state);
    + target_put_sess_cmd(&cmd->se_cmd);
    return 0;
    }
    EXPORT_SYMBOL(iscsit_handle_task_mgt_cmd);

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