Re: [PATCH] libiscsi: fix UAF when iscsi_conn_get_param and iscsi_conn_teardown concurrent

[Lee Duncan <lduncan@suse.com>]

On 12/20/21 3:39 AM, lixiaokeng wrote:
> |- iscsi_if_destroy_conn            |-dev_attr_show
>  |-iscsi_conn_teardown
>   |-spin_lock_bh                     |-iscsi_sw_tcp_conn_get_param
> 
>   |-kfree(conn->persistent_address)   |-iscsi_conn_get_param
>   |-kfree(conn->local_ipaddr)
>                                        ==>|-read persistent_address
>                                        ==>|-read local_ipaddr
>   |-spin_unlock_bh
> 
> when iscsi_conn_teardown and iscsi_conn_get_param happen in parallel,
> may trigger UAF issues.
> 
> Signed-off-by: Lixiaokeng<lixiaokeng@huawei.com>
> Signed-off-by: Linfeilong<linfeilong@huawei.com>
> Reported-by: Lu Tixiong<lutianxiong@huawei.com>
> ---
>  drivers/scsi/libiscsi.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
> index 284b939fb1ea..059dae8909ee 100644
> --- a/drivers/scsi/libiscsi.c
> +++ b/drivers/scsi/libiscsi.c
> @@ -3100,6 +3100,8 @@ void iscsi_conn_teardown(struct iscsi_cls_conn *cls_conn)
>  {
>  	struct iscsi_conn *conn = cls_conn->dd_data;
>  	struct iscsi_session *session = conn->session;
> +	char *tmp_persistent_address = conn->persistent_address;
> +	char *tmp_local_ipaddr = conn->local_ipaddr;
> 
>  	del_timer_sync(&conn->transport_timer);
> 
> @@ -3121,8 +3123,6 @@ void iscsi_conn_teardown(struct iscsi_cls_conn *cls_conn)
>  	spin_lock_bh(&session->frwd_lock);
>  	free_pages((unsigned long) conn->data,
>  		   get_order(ISCSI_DEF_MAX_RECV_SEG_LEN));
> -	kfree(conn->persistent_address);
> -	kfree(conn->local_ipaddr);
>  	/* regular RX path uses back_lock */
>  	spin_lock_bh(&session->back_lock);
>  	kfifo_in(&session->cmdpool.queue, (void*)&conn->login_task,
> @@ -3134,6 +3134,8 @@ void iscsi_conn_teardown(struct iscsi_cls_conn *cls_conn)
>  	mutex_unlock(&session->eh_mutex);
> 
>  	iscsi_destroy_conn(cls_conn);
> +	kfree(tmp_persistent_address);
> +	kfree(tmp_local_ipaddr);
>  }
>  EXPORT_SYMBOL_GPL(iscsi_conn_teardown);
> 

Reviewed-by: Lee Duncan <lduncan@suse.com>