[PATCH] RDMA/cma: Fix listener leak in rdma_cma_listen_on_all() failure

[Tao Liu]

If cma_listen_on_all() fails it leaves the per-device ID still on the
listen_list but the state is not set to RDMA_CM_ADDR_BOUND.

When the cmid is eventually destroyed cma_cancel_listens() is not called
due to the wrong state, however the per-device IDs are still holding the
refcount preventing the ID from being destroyed, thus deadlocking:

 task:rping state:D stack:   0 pid:19605 ppid: 47036 flags:0x00000084
 Call Trace:
  __schedule+0x29a/0x780
  ? free_unref_page_commit+0x9b/0x110
  schedule+0x3c/0xa0
  schedule_timeout+0x215/0x2b0
  ? __flush_work+0x19e/0x1e0
  wait_for_completion+0x8d/0xf0
  _destroy_id+0x144/0x210 [rdma_cm]
  ucma_close_id+0x2b/0x40 [rdma_ucm]
  __destroy_id+0x93/0x2c0 [rdma_ucm]
  ? __xa_erase+0x4a/0xa0
  ucma_destroy_id+0x9a/0x120 [rdma_ucm]
  ucma_write+0xb8/0x130 [rdma_ucm]
  vfs_write+0xb4/0x250
  ksys_write+0xb5/0xd0
  ? syscall_trace_enter.isra.19+0x123/0x190
  do_syscall_64+0x33/0x40
  entry_SYSCALL_64_after_hwframe+0x44/0xa9

Ensure that cma_listen_on_all() atomically unwinds its action under the
lock during error and reorganize how destroy_id works to be directly
sensitive to the listen list not indirectly through the state and some
other random collection of variables.

Fixes: c80a0c52d85c ("RDMA/cma: Add missing error handling of listen_id")
Link: https://lore.kernel.org/r/20210913093344.17230-1-thomas.liu@xxxxxxxxx
Signed-off-by: Tao Liu <thomas.liu@xxxxxxxxx>
Reviewed-by: Leon Romanovsky <leonro@xxxxxxxxxx>
Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
---
 drivers/infiniband/core/cma.c | 28 ++++++++++++++++++++--------
 1 file changed, 20 insertions(+), 8 deletions(-)

diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
index 86ee3b01b3ee47..be6beee1dd4c5e 100644
--- a/drivers/infiniband/core/cma.c
+++ b/drivers/infiniband/core/cma.c
@@ -1746,16 +1746,17 @@ static void cma_cancel_route(struct rdma_id_private *id_priv)
 	}
 }
 
-static void cma_cancel_listens(struct rdma_id_private *id_priv)
+static void _cma_cancel_listens(struct rdma_id_private *id_priv)
 {
 	struct rdma_id_private *dev_id_priv;
 
+	lockdep_assert_held(&lock);
+
 	/*
 	 * Remove from listen_any_list to prevent added devices from spawning
 	 * additional listen requests.
 	 */
-	mutex_lock(&lock);
-	list_del(&id_priv->list);
+	list_del_init(&id_priv->list);
 
 	while (!list_empty(&id_priv->listen_list)) {
 		dev_id_priv = list_entry(id_priv->listen_list.next,
@@ -1768,6 +1769,20 @@ static void cma_cancel_listens(struct rdma_id_private *id_priv)
 		rdma_destroy_id(&dev_id_priv->id);
 		mutex_lock(&lock);
 	}
+}
+
+static void cma_cancel_listens(struct rdma_id_private *id_priv)
+{
+	/*
+	 * During _destroy_id() it is not possible for this value to transition
+	 * from empty to !empty, test it outside to lock to avoid taking a
+	 * global lock on every destroy. Only listen all cases will have
+	 * something to do
+	 */
+	if (list_empty(&id_priv->list))
+		return;
+	mutex_lock(&lock);
+	_cma_cancel_listens(id_priv);
 	mutex_unlock(&lock);
 }
 
@@ -1781,10 +1796,6 @@ static void cma_cancel_operation(struct rdma_id_private *id_priv,
 	case RDMA_CM_ROUTE_QUERY:
 		cma_cancel_route(id_priv);
 		break;
-	case RDMA_CM_LISTEN:
-		if (cma_any_addr(cma_src_addr(id_priv)) && !id_priv->cma_dev)
-			cma_cancel_listens(id_priv);
-		break;
 	default:
 		break;
 	}
@@ -1855,6 +1866,7 @@ static void cma_leave_mc_groups(struct rdma_id_private *id_priv)
 static void _destroy_id(struct rdma_id_private *id_priv,
 			enum rdma_cm_state state)
 {
+	cma_cancel_listens(id_priv);
 	cma_cancel_operation(id_priv, state);
 
 	rdma_restrack_del(&id_priv->res);
@@ -2579,7 +2591,7 @@ static int cma_listen_on_all(struct rdma_id_private *id_priv)
 	return 0;
 
 err_listen:
-	list_del(&id_priv->list);
+	_cma_cancel_listens(id_priv);
 	mutex_unlock(&lock);
 	if (to_destroy)
 		rdma_destroy_id(&to_destroy->id);
-- 
2.33.0