RDMA/cma: Use correct address when leaving multicast group

In RoCE we should use cma_iboe_set_mgid() and not cma_set_mgid to generate
the mgid, otherwise we will generate an IGMP for an incorrect address.

Fixes: b5de0c6 ("RDMA/cma: Fix use after free race in roce multicast join")
Link: https://lore.kernel.org/r/913bc6783fd7a95fe71ad9454e01653ee6fb4a9a.1642491047.git.leonro@nvidia.com
Signed-off-by: Maor Gottlieb <maorg@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

Author: maorgottlieb

drivers/infiniband/core/cma.c

@@ -67,8 +67,8 @@ static const char * const cma_events[] = {
 	[RDMA_CM_EVENT_TIMEWAIT_EXIT]	 = "timewait exit",
 };
 
-static void cma_set_mgid(struct rdma_id_private *id_priv, struct sockaddr *addr,
-			 union ib_gid *mgid);
+static void cma_iboe_set_mgid(struct sockaddr *addr, union ib_gid *mgid,
+			      enum ib_gid_type gid_type);
 
 const char *__attribute_const__ rdma_event_msg(enum rdma_cm_event_type event)
 {
@@ -1846,17 +1846,19 @@ static void destroy_mc(struct rdma_id_private *id_priv,
 		if (dev_addr->bound_dev_if)
 			ndev = dev_get_by_index(dev_addr->net,
 						dev_addr->bound_dev_if);
-		if (ndev) {
+		if (ndev && !send_only) {
+			enum ib_gid_type gid_type;
 			union ib_gid mgid;
 
-			cma_set_mgid(id_priv, (struct sockaddr *)&mc->addr,
-				     &mgid);
-
-			if (!send_only)
-				cma_igmp_send(ndev, &mgid, false);
-
-			dev_put(ndev);
+			gid_type = id_priv->cma_dev->default_gid_type
+					   [id_priv->id.port_num -
+					    rdma_start_port(
+						    id_priv->cma_dev->device)];
+			cma_iboe_set_mgid((struct sockaddr *)&mc->addr, &mgid,
+					  gid_type);
+			cma_igmp_send(ndev, &mgid, false);
 		}
+		dev_put(ndev);
 
 		cancel_work_sync(&mc->iboe_join.work);
 	}