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    Subject[PATCH 3.19 122/123] iscsi-target: Avoid early conn_logout_comp for iser connections
    Date
    3.19-stable review patch.  If anyone has any objections, please let me know.

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

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

    commit f068fbc82e7696d67b1bb8189306865bedf368b6 upstream.

    This patch fixes a iser specific logout bug where early complete()
    of conn->conn_logout_comp in iscsit_close_connection() was causing
    isert_wait4logout() to complete too soon, triggering a use after
    free NULL pointer dereference of iscsi_conn memory.

    The complete() was originally added for traditional iscsi-target
    when a ISCSI_LOGOUT_OP failed in iscsi_target_rx_opcode(), but given
    iser-target does not wait in logout failure, this special case needs
    to be avoided.

    Reported-by: Sagi Grimberg <sagig@mellanox.com>
    Cc: Sagi Grimberg <sagig@mellanox.com>
    Cc: Slava Shwartsman <valyushash@gmail.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 | 14 ++++++++++----
    1 file changed, 10 insertions(+), 4 deletions(-)

    --- a/drivers/target/iscsi/iscsi_target.c
    +++ b/drivers/target/iscsi/iscsi_target.c
    @@ -4221,11 +4221,17 @@ int iscsit_close_connection(
    pr_debug("Closing iSCSI connection CID %hu on SID:"
    " %u\n", conn->cid, sess->sid);
    /*
    - * Always up conn_logout_comp just in case the RX Thread is sleeping
    - * and the logout response never got sent because the connection
    - * failed.
    + * Always up conn_logout_comp for the traditional TCP case just in case
    + * the RX Thread in iscsi_target_rx_opcode() is sleeping and the logout
    + * response never got sent because the connection failed.
    + *
    + * However for iser-target, isert_wait4logout() is using conn_logout_comp
    + * to signal logout response TX interrupt completion. Go ahead and skip
    + * this for iser since isert_rx_opcode() does not wait on logout failure,
    + * and to avoid iscsi_conn pointer dereference in iser-target code.
    */
    - complete(&conn->conn_logout_comp);
    + if (conn->conn_transport->transport_type == ISCSI_TCP)
    + complete(&conn->conn_logout_comp);

    iscsi_release_thread_set(conn);




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