From e496ae690b2faff751e1849fb97b060615e21f28 Mon Sep 17 00:00:00 2001 From: Russell King Date: Thu, 24 Sep 2015 20:35:57 +0100 Subject: [PATCH] net: dsa: fix of_mdio_find_bus() device refcount leak Current users of of_mdio_find_bus() leak a struct device refcount, as they fail to clean up the reference obtained inside class_find_device(). Fix the DSA code to properly refcount the returned MDIO bus by: 1. taking a reference on the struct device whenever we assign it to pd->chip[x].host_dev. 2. dropping the reference when we overwrite the existing reference. 3. dropping the reference when we free the data structure. 4. dropping the initial reference we obtained after setting up the platform data structure, or on failure. In step 2 above, where we obtain a new MDIO bus, there is no need to take a reference on it as we would only have to drop it immediately after assignment again, iow: put_device(cd->host_dev); /* drop original assignment ref */ cd->host_dev = get_device(&mdio_bus_switch->dev); /* get our ref */ put_device(&mdio_bus_switch->dev); /* drop of_mdio_find_bus ref */ Signed-off-by: Russell King Signed-off-by: David S. Miller --- net/dsa/dsa.c | 38 +++++++++++++++++++++++++++++++------- 1 file changed, 31 insertions(+), 7 deletions(-) diff --git a/net/dsa/dsa.c b/net/dsa/dsa.c index 76e3800765f8..bf4ba15fb780 100644 --- a/net/dsa/dsa.c +++ b/net/dsa/dsa.c @@ -634,6 +634,10 @@ static void dsa_of_free_platform_data(struct dsa_platform_data *pd) port_index++; } kfree(pd->chip[i].rtable); + + /* Drop our reference to the MDIO bus device */ + if (pd->chip[i].host_dev) + put_device(pd->chip[i].host_dev); } kfree(pd->chip); } @@ -661,16 +665,22 @@ static int dsa_of_probe(struct device *dev) return -EPROBE_DEFER; ethernet = of_parse_phandle(np, "dsa,ethernet", 0); - if (!ethernet) - return -EINVAL; + if (!ethernet) { + ret = -EINVAL; + goto out_put_mdio; + } ethernet_dev = of_find_net_device_by_node(ethernet); - if (!ethernet_dev) - return -EPROBE_DEFER; + if (!ethernet_dev) { + ret = -EPROBE_DEFER; + goto out_put_mdio; + } pd = kzalloc(sizeof(*pd), GFP_KERNEL); - if (!pd) - return -ENOMEM; + if (!pd) { + ret = -ENOMEM; + goto out_put_mdio; + } dev->platform_data = pd; pd->of_netdev = ethernet_dev; @@ -691,7 +701,9 @@ static int dsa_of_probe(struct device *dev) cd = &pd->chip[chip_index]; cd->of_node = child; - cd->host_dev = &mdio_bus->dev; + + /* When assigning the host device, increment its refcount */ + cd->host_dev = get_device(&mdio_bus->dev); sw_addr = of_get_property(child, "reg", NULL); if (!sw_addr) @@ -711,6 +723,12 @@ static int dsa_of_probe(struct device *dev) ret = -EPROBE_DEFER; goto out_free_chip; } + + /* Drop the mdio_bus device ref, replacing the host + * device with the mdio_bus_switch device, keeping + * the refcount from of_mdio_find_bus() above. + */ + put_device(cd->host_dev); cd->host_dev = &mdio_bus_switch->dev; } @@ -744,6 +762,10 @@ static int dsa_of_probe(struct device *dev) } } + /* The individual chips hold their own refcount on the mdio bus, + * so drop ours */ + put_device(&mdio_bus->dev); + return 0; out_free_chip: @@ -751,6 +773,8 @@ out_free_chip: out_free: kfree(pd); dev->platform_data = NULL; +out_put_mdio: + put_device(&mdio_bus->dev); return ret; } -- 2.20.1