RDMA/core: Use size_{add,sub,mul}() in calls to struct_size()

If, for any reason, the open-coded arithmetic causes a wraparound,
the protection that `struct_size()` provides against potential integer
overflows is defeated. Fix this by hardening calls to `struct_size()`
with `size_add()`, `size_sub()` and `size_mul()`.

Fixes: 467f432a ("RDMA/core: Split port and device counter sysfs attributes")
Fixes: a4676388 ("RDMA/core: Simplify how the gid_attrs sysfs is created")
Fixes: e9dd5daf ("IB/umad: Refactor code to use cdev_device_add()")
Fixes: 324e227e ("RDMA/device: Add ib_device_get_by_netdev()")
Fixes: 5aad26a7 ("IB/core: Use struct_size() in kzalloc()")
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/ZQdt4NsJFwwOYxUR@workSigned-off-by: Leon Romanovsky <leon@kernel.org>

drivers/infiniband/core/device.c

@@ -804,7 +804,7 @@ static int alloc_port_data(struct ib_device *device)
 	 * empty slots at the beginning.
 	 */
 	pdata_rcu = kzalloc(struct_size(pdata_rcu, pdata,
-					rdma_end_port(device) + 1),
+					size_add(rdma_end_port(device), 1)),
 			    GFP_KERNEL);
 	if (!pdata_rcu)
 		return -ENOMEM;

drivers/infiniband/core/sa_query.c

@@ -2159,7 +2159,9 @@ static int ib_sa_add_one(struct ib_device *device)
 	s = rdma_start_port(device);
 	e = rdma_end_port(device);
 
-	sa_dev = kzalloc(struct_size(sa_dev, port, e - s + 1), GFP_KERNEL);
+	sa_dev = kzalloc(struct_size(sa_dev, port,
+				     size_add(size_sub(e, s), 1)),
+			 GFP_KERNEL);
 	if (!sa_dev)
 		return -ENOMEM;
 

drivers/infiniband/core/sysfs.c

@@ -903,7 +903,7 @@ alloc_hw_stats_device(struct ib_device *ibdev)
 	 * Two extra attribue elements here, one for the lifespan entry and
 	 * one to NULL terminate the list for the sysfs core code
 	 */
-	data = kzalloc(struct_size(data, attrs, stats->num_counters + 1),
+	data = kzalloc(struct_size(data, attrs, size_add(stats->num_counters, 1)),
 		       GFP_KERNEL);
 	if (!data)
 		goto err_free_stats;
@@ -1009,7 +1009,7 @@ alloc_hw_stats_port(struct ib_port *port, struct attribute_group *group)
 	 * Two extra attribue elements here, one for the lifespan entry and
 	 * one to NULL terminate the list for the sysfs core code
 	 */
-	data = kzalloc(struct_size(data, attrs, stats->num_counters + 1),
+	data = kzalloc(struct_size(data, attrs, size_add(stats->num_counters, 1)),
 		       GFP_KERNEL);
 	if (!data)
 		goto err_free_stats;
@@ -1140,7 +1140,7 @@ static int setup_gid_attrs(struct ib_port *port,
 	int ret;
 
 	gid_attr_group = kzalloc(struct_size(gid_attr_group, attrs_list,
-					     attr->gid_tbl_len * 2),
+					     size_mul(attr->gid_tbl_len, 2)),
 				 GFP_KERNEL);
 	if (!gid_attr_group)
 		return -ENOMEM;
@@ -1205,8 +1205,8 @@ static struct ib_port *setup_port(struct ib_core_device *coredev, int port_num,
 	int ret;
 
 	p = kvzalloc(struct_size(p, attrs_list,
-				attr->gid_tbl_len + attr->pkey_tbl_len),
-		    GFP_KERNEL);
+				size_add(attr->gid_tbl_len, attr->pkey_tbl_len)),
+		     GFP_KERNEL);
 	if (!p)
 		return ERR_PTR(-ENOMEM);
 	p->ibdev = device;

drivers/infiniband/core/user_mad.c

@@ -1378,7 +1378,9 @@ static int ib_umad_add_one(struct ib_device *device)
 	s = rdma_start_port(device);
 	e = rdma_end_port(device);
 
-	umad_dev = kzalloc(struct_size(umad_dev, ports, e - s + 1), GFP_KERNEL);
+	umad_dev = kzalloc(struct_size(umad_dev, ports,
+				       size_add(size_sub(e, s), 1)),
+			   GFP_KERNEL);
 	if (!umad_dev)
 		return -ENOMEM;