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: c80a0c52d85c ("RDMA/cma: Add missing error handling of listen_id")
Link: https://lore.kernel.org/r/20201118133756.GK244516@ziepe.ca
Reported-by: syzbot+1bc48bf7f78253f664a9@syzkaller.appspotmail.com
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
index 4585f65..c06c87a 100644 (file)
--- a/drivers/infiniband/core/cma.c
+++ b/drivers/infiniband/core/cma.c
@@ -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;
@@ -2528,25 +2529,31 @@ 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;
@@ -2554,6 +2561,8 @@ static int cma_listen_on_all(struct rdma_id_private *id_priv)
 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: