Commit d490ee52 authored by Jason Gunthorpe's avatar Jason Gunthorpe
Browse files

RDMA/cma: Fix locking for the RDMA_CM_LISTEN state 

There is a strange unlocked read of the ID state when checking for
reuseaddr. This is because an ID cannot be reusable once it becomes a
listening ID. Instead of using the state to exclude reuse, just clear it
as part of rdma_listen()'s flow to convert reusable into not reusable.

Once a ID goes to listen there is no way back out, and the only use of
reusable is on the bind_list check.

Finally, update the checks under handler_mutex to use READ_ONCE and audit
that once RDMA_CM_LISTEN is observed in a req callback it is stable under
the handler_mutex.

Link: https://lore.kernel.org/r/20200902081122.745412-4-leon@kernel.org


Signed-off-by: default avatarLeon Romanovsky <leonro@nvidia.com>
Signed-off-by: default avatarJason Gunthorpe <jgg@nvidia.com>
parent 732d41c5

drivers/infiniband/core/cma.c

+18 −18
Original line number Diff line number Diff line
@@ -2195,7 +2195,7 @@ static int cma_ib_req_handler(struct ib_cm_id *cm_id, 
	}



	mutex_lock(&listen_id->handler_mutex);

	if (listen_id->state != RDMA_CM_LISTEN) {

	if (READ_ONCE(listen_id->state) != RDMA_CM_LISTEN) {

		ret = -ECONNABORTED;

		goto err_unlock;

	}
@@ -2373,7 +2373,7 @@ static int iw_conn_req_handler(struct iw_cm_id *cm_id, 
	listen_id = cm_id->context;



	mutex_lock(&listen_id->handler_mutex);

	if (listen_id->state != RDMA_CM_LISTEN)

	if (READ_ONCE(listen_id->state) != RDMA_CM_LISTEN)

		goto out;



	/* Create a new RDMA id for the new IW CM ID */
@@ -3327,7 +3327,8 @@ int rdma_set_reuseaddr(struct rdma_cm_id *id, int reuse) 


	id_priv = container_of(id, struct rdma_id_private, id);

	spin_lock_irqsave(&id_priv->lock, flags);

	if (reuse || id_priv->state == RDMA_CM_IDLE) {

	if ((reuse && id_priv->state != RDMA_CM_LISTEN) ||

	    id_priv->state == RDMA_CM_IDLE) {

		id_priv->reuseaddr = reuse;

		ret = 0;

	} else {
@@ -3521,8 +3522,7 @@ static int cma_check_port(struct rdma_bind_list *bind_list, 
		if (id_priv == cur_id)

			continue;



		if ((cur_id->state != RDMA_CM_LISTEN) && reuseaddr &&

		    cur_id->reuseaddr)

		if (reuseaddr && cur_id->reuseaddr)

			continue;



		cur_addr = cma_src_addr(cur_id);
@@ -3563,18 +3563,6 @@ static int cma_use_port(enum rdma_ucm_port_space ps, 
	return ret;

}



static int cma_bind_listen(struct rdma_id_private *id_priv)

{

	struct rdma_bind_list *bind_list = id_priv->bind_list;

	int ret = 0;



	mutex_lock(&lock);

	if (bind_list->owners.first->next)

		ret = cma_check_port(bind_list, id_priv, 0);

	mutex_unlock(&lock);

	return ret;

}



static enum rdma_ucm_port_space

cma_select_inet_ps(struct rdma_id_private *id_priv)

{
@@ -3683,8 +3671,16 @@ int rdma_listen(struct rdma_cm_id *id, int backlog) 
			return -EINVAL;

	}



	/*

	 * Once the ID reaches RDMA_CM_LISTEN it is not allowed to be reusable

	 * any more, and has to be unique in the bind list.

	 */

	if (id_priv->reuseaddr) {

		ret = cma_bind_listen(id_priv);

		mutex_lock(&lock);

		ret = cma_check_port(id_priv->bind_list, id_priv, 0);

		if (!ret)

			id_priv->reuseaddr = 0;

		mutex_unlock(&lock);

		if (ret)

			goto err;

	}
@@ -3709,6 +3705,10 @@ int rdma_listen(struct rdma_cm_id *id, int backlog) 
	return 0;

err:

	id_priv->backlog = 0;

	/*

	 * All the failure paths that lead here will not allow the req_handler's

	 * to have run.

	 */

	cma_comp_exch(id_priv, RDMA_CM_LISTEN, RDMA_CM_ADDR_BOUND);

	return ret;

}

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