Commit dd37d2f5 authored by Jason Gunthorpe's avatar Jason Gunthorpe
Browse files

RDMA/cma: Fix deadlock on &lock in rdma_cma_listen_on_all() error unwind 

rdma_detroy_id() cannot be called under &lock - we must instead keep the
error'd ID around until &lock can be released, then destroy it.

This is complicated by the usual way listen IDs are destroyed through
cma_process_remove() which can run at any time and will asynchronously
destroy the same ID.

Remove the ID from visiblity of cma_process_remove() before going down the
destroy path outside the locking.

Fixes: c80a0c52 ("RDMA/cma: Add missing error handling of listen_id")
Link: https://lore.kernel.org/r/20201118133756.GK244516@ziepe.ca


Reported-by: default avatar <syzbot+1bc48bf7f78253f664a9@syzkaller.appspotmail.com>
Reviewed-by: default avatarLeon Romanovsky <leonro@nvidia.com>
Signed-off-by: default avatarJason Gunthorpe <jgg@nvidia.com>
parent 6f6e2dcb

drivers/infiniband/core/cma.c

+18 −7
Original line number Diff line number Diff line
@@ -2496,7 +2496,8 @@ static int cma_listen_handler(struct rdma_cm_id *id, 
}



static int cma_listen_on_dev(struct rdma_id_private *id_priv,

			     struct cma_device *cma_dev)

			     struct cma_device *cma_dev,

			     struct rdma_id_private **to_destroy)

{

	struct rdma_id_private *dev_id_priv;

	struct net *net = id_priv->id.route.addr.dev_addr.net;
@@ -2504,6 +2505,7 @@ static int cma_listen_on_dev(struct rdma_id_private *id_priv, 


	lockdep_assert_held(&lock);



	*to_destroy = NULL;

	if (cma_family(id_priv) == AF_IB && !rdma_cap_ib_cm(cma_dev->device, 1))

		return 0;
@@ -2518,7 +2520,6 @@ static int cma_listen_on_dev(struct rdma_id_private *id_priv, 
	       rdma_addr_size(cma_src_addr(id_priv)));



	_cma_attach_to_dev(dev_id_priv, cma_dev);

	list_add_tail(&dev_id_priv->listen_list, &id_priv->listen_list);

	cma_id_get(id_priv);

	dev_id_priv->internal_id = 1;

	dev_id_priv->afonly = id_priv->afonly;
@@ -2528,32 +2529,40 @@ static int cma_listen_on_dev(struct rdma_id_private *id_priv, 
	ret = rdma_listen(&dev_id_priv->id, id_priv->backlog);

	if (ret)

		goto err_listen;

	list_add_tail(&dev_id_priv->listen_list, &id_priv->listen_list);

	return 0;

err_listen:

	list_del(&id_priv->listen_list);

	/* Caller must destroy this after releasing lock */

	*to_destroy = dev_id_priv;

	dev_warn(&cma_dev->device->dev, "RDMA CMA: %s, error %d\n", __func__, ret);

	rdma_destroy_id(&dev_id_priv->id);

	return ret;

}



static int cma_listen_on_all(struct rdma_id_private *id_priv)

{

	struct rdma_id_private *to_destroy;

	struct cma_device *cma_dev;

	int ret;



	mutex_lock(&lock);

	list_add_tail(&id_priv->list, &listen_any_list);

	list_for_each_entry(cma_dev, &dev_list, list) {

		ret = cma_listen_on_dev(id_priv, cma_dev);

		if (ret)

		ret = cma_listen_on_dev(id_priv, cma_dev, &to_destroy);

		if (ret) {

			/* Prevent racing with cma_process_remove() */

			if (to_destroy)

				list_del_init(&to_destroy->list);

			goto err_listen;

		}

	}

	mutex_unlock(&lock);

	return 0;



err_listen:

	list_del(&id_priv->list);

	mutex_unlock(&lock);

	if (to_destroy)

		rdma_destroy_id(&to_destroy->id);

	return ret;

}
@@ -4855,6 +4864,7 @@ static void cma_process_remove(struct cma_device *cma_dev) 


static int cma_add_one(struct ib_device *device)

{

	struct rdma_id_private *to_destroy;

	struct cma_device *cma_dev;

	struct rdma_id_private *id_priv;

	unsigned int i;
@@ -4902,7 +4912,7 @@ static int cma_add_one(struct ib_device *device) 
	mutex_lock(&lock);

	list_add_tail(&cma_dev->list, &dev_list);

	list_for_each_entry(id_priv, &listen_any_list, list) {

		ret = cma_listen_on_dev(id_priv, cma_dev);

		ret = cma_listen_on_dev(id_priv, cma_dev, &to_destroy);

		if (ret)

			goto free_listen;

	}
@@ -4915,6 +4925,7 @@ free_listen: 
	list_del(&cma_dev->list);

	mutex_unlock(&lock);



	/* cma_process_remove() will delete to_destroy */

	cma_process_remove(cma_dev);

	kfree(cma_dev->default_roce_tos);

free_gid_type:

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