Messages in this thread | | | Subject | Re: [PATCH 18/26] target/iscsi: Allocate session IDs from an IDA | From | Mike Christie <> | Date | Thu, 26 Jul 2018 11:48:22 -0500 |
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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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