RDMA/cma: Fix rdma_resolve_route() memory leak

stable inclusion
from linux-4.19.198
commit 4893c938f2a140a74be91779e45e4a7fa111198f

--------------------------------

[ Upstream commit 74f160ea ]

Fix a memory leak when "mda_resolve_route() is called more than once on
the same "rdma_cm_id".

This is possible if cma_query_handler() triggers the
RDMA_CM_EVENT_ROUTE_ERROR flow which puts the state machine back and
allows rdma_resolve_route() to be called again.

Link: https://lore.kernel.org/r/f6662b7b-bdb7-2706-1e12-47c61d3474b6@oracle.comSigned-off-by: NGerd Rausch <gerd.rausch@oracle.com>
Signed-off-by: NJason Gunthorpe <jgg@nvidia.com>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

drivers/infiniband/core/cma.c

@@ -2558,7 +2558,8 @@ static int cma_resolve_ib_route(struct rdma_id_private *id_priv, int timeout_ms)
 
 	cma_init_resolve_route_work(work, id_priv);
 
-	route->path_rec = kmalloc(sizeof *route->path_rec, GFP_KERNEL);
+	if (!route->path_rec)
+		route->path_rec = kmalloc(sizeof *route->path_rec, GFP_KERNEL);
 	if (!route->path_rec) {
 		ret = -ENOMEM;
 		goto err1;