[PATCH 5.6 042/177] mlxsw: spectrum: Fix use-after-free of split/unsplit/type_set in case reload fails

[Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>]

From: Jiri Pirko <jiri@xxxxxxxxxxxx>

commit 4340f42f207eacb81e7a6b6bb1e3b6afad9a2e26 upstream.

In case of reload fail, the mlxsw_sp->ports contains a pointer to a
freed memory (either by reload_down() or reload_up() error path).
Fix this by initializing the pointer to NULL and checking it before
dereferencing in split/unsplit/type_set callpaths.

Fixes: 24cc68ad6c46 ("mlxsw: core: Add support for reload")
Reported-by: Danielle Ratson <danieller@xxxxxxxxxxxx>
Signed-off-by: Jiri Pirko <jiri@xxxxxxxxxxxx>
Signed-off-by: Ido Schimmel <idosch@xxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/net/ethernet/mellanox/mlxsw/spectrum.c |   14 ++++++++++++--
 drivers/net/ethernet/mellanox/mlxsw/switchx2.c |    8 ++++++++
 2 files changed, 20 insertions(+), 2 deletions(-)

--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
@@ -4043,6 +4043,7 @@ static void mlxsw_sp_ports_remove(struct
 			mlxsw_sp_port_remove(mlxsw_sp, i);
 	mlxsw_sp_cpu_port_remove(mlxsw_sp);
 	kfree(mlxsw_sp->ports);
+	mlxsw_sp->ports = NULL;
 }
 
 static int mlxsw_sp_ports_create(struct mlxsw_sp *mlxsw_sp)
@@ -4079,6 +4080,7 @@ err_port_create:
 	mlxsw_sp_cpu_port_remove(mlxsw_sp);
 err_cpu_port_create:
 	kfree(mlxsw_sp->ports);
+	mlxsw_sp->ports = NULL;
 	return err;
 }
 
@@ -4200,6 +4202,14 @@ static int mlxsw_sp_local_ports_offset(s
 	return mlxsw_core_res_get(mlxsw_core, local_ports_in_x_res_id);
 }
 
+static struct mlxsw_sp_port *
+mlxsw_sp_port_get_by_local_port(struct mlxsw_sp *mlxsw_sp, u8 local_port)
+{
+	if (mlxsw_sp->ports && mlxsw_sp->ports[local_port])
+		return mlxsw_sp->ports[local_port];
+	return NULL;
+}
+
 static int mlxsw_sp_port_split(struct mlxsw_core *mlxsw_core, u8 local_port,
 			       unsigned int count,
 			       struct netlink_ext_ack *extack)
@@ -4213,7 +4223,7 @@ static int mlxsw_sp_port_split(struct ml
 	int i;
 	int err;
 
-	mlxsw_sp_port = mlxsw_sp->ports[local_port];
+	mlxsw_sp_port = mlxsw_sp_port_get_by_local_port(mlxsw_sp, local_port);
 	if (!mlxsw_sp_port) {
 		dev_err(mlxsw_sp->bus_info->dev, "Port number \"%d\" does not exist\n",
 			local_port);
@@ -4308,7 +4318,7 @@ static int mlxsw_sp_port_unsplit(struct
 	int offset;
 	int i;
 
-	mlxsw_sp_port = mlxsw_sp->ports[local_port];
+	mlxsw_sp_port = mlxsw_sp_port_get_by_local_port(mlxsw_sp, local_port);
 	if (!mlxsw_sp_port) {
 		dev_err(mlxsw_sp->bus_info->dev, "Port number \"%d\" does not exist\n",
 			local_port);
--- a/drivers/net/ethernet/mellanox/mlxsw/switchx2.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/switchx2.c
@@ -1259,6 +1259,7 @@ static void mlxsw_sx_ports_remove(struct
 		if (mlxsw_sx_port_created(mlxsw_sx, i))
 			mlxsw_sx_port_remove(mlxsw_sx, i);
 	kfree(mlxsw_sx->ports);
+	mlxsw_sx->ports = NULL;
 }
 
 static int mlxsw_sx_ports_create(struct mlxsw_sx *mlxsw_sx)
@@ -1293,6 +1294,7 @@ err_port_module_info_get:
 		if (mlxsw_sx_port_created(mlxsw_sx, i))
 			mlxsw_sx_port_remove(mlxsw_sx, i);
 	kfree(mlxsw_sx->ports);
+	mlxsw_sx->ports = NULL;
 	return err;
 }
 
@@ -1376,6 +1378,12 @@ static int mlxsw_sx_port_type_set(struct
 	u8 module, width;
 	int err;
 
+	if (!mlxsw_sx->ports || !mlxsw_sx->ports[local_port]) {
+		dev_err(mlxsw_sx->bus_info->dev, "Port number \"%d\" does not exist\n",
+			local_port);
+		return -EINVAL;
+	}
+
 	if (new_type == DEVLINK_PORT_TYPE_AUTO)
 		return -EOPNOTSUPP;