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    SubjectRe: [PATCH 18/26] target/iscsi: Allocate session IDs from an IDA
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    On 06/21/2018 04:28 PM, Matthew Wilcox wrote:

    > @@ -1163,11 +1157,9 @@ void iscsi_target_login_sess_out(struct iscsi_conn *conn,
    > goto old_sess_out;
    > if (conn->sess->se_sess)
    > transport_free_session(conn->sess->se_sess);
    > - if (conn->sess->session_index != 0) {
    > - spin_lock_bh(&sess_idr_lock);
    > - idr_remove(&sess_idr, conn->sess->session_index);
    > - spin_unlock_bh(&sess_idr_lock);

    This code looks buggy. We will probably NULL pointer oops before we hit it.

    It looks like the session_index check was supposed to detect when login
    fails in the middle of doing login, so that code probably wanted to do:

    idr_alloc(&sess_idr, NULL, 1, 0, GFP_NOWAIT);

    The problem is that iscsi_login_zero_tsih_s1 sets conn->sess early in
    iscsi_login_set_conn_values. If the function fails later like when we
    alloc the idr it does kfree(sess) and leaves the conn->sess pointer set.
    iscsi_login_zero_tsih_s1 then returns -Exyz and we then call
    iscsi_target_login_sess_out and access the freed memory above.

    So I am not sure what we want to do here for your patch since it is not
    adding any new bugs. Just merge your patch now and I can send a fix for
    the above bug over it?


    > - }
    > + /* Um, 0 is a valid ID. I suppose we never free it? */
    > + if (conn->sess->session_index != 0)
    > + ida_free(&sess_ida, conn->sess->session_index);
    > kfree(conn->sess->sess_ops);
    > kfree(conn->sess);
    > conn->sess = NULL;
    >

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