RDMA/restrack: Increment CQ restrack object before committing

Once the uobj is committed it is immediately possible another thread
could destroy it, which worst case, can result in a use-after-free
of the restrack objects.

Cc: syzkaller <syzkaller@googlegroups.com>
Fixes: 08f294a ("RDMA/core: Add resource tracking for create and destroy CQs")
Reported-by: Noa Osherovich <noaos@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/core/uverbs_cmd.c

@@ -1030,14 +1030,14 @@ static struct ib_ucq_object *create_cq(struct ib_uverbs_file *file,
 	resp.response_length = offsetof(typeof(resp), response_length) +
 		sizeof(resp.response_length);
 
+	cq->res.type = RDMA_RESTRACK_CQ;
+	rdma_restrack_add(&cq->res);
+
 	ret = cb(file, obj, &resp, ucore, context);
 	if (ret)
 		goto err_cb;
 
 	uobj_alloc_commit(&obj->uobject);
-	cq->res.type = RDMA_RESTRACK_CQ;
-	rdma_restrack_add(&cq->res);
-
 	return obj;
 
 err_cb: