virt_wifi_newlink() calls netdev_upper_dev_link() and it internally
holds reference count of lower interface.
Current code does not release a reference count of the lower interface
when the lower interface is being deleted.
So, reference count leaks occur.
Test commands:
ip link add dummy0 type dummy
ip link add vw1 link dummy0 type virt_wifi
Splat looks like:
[ 182.001918][ T1333] WARNING: CPU: 0 PID: 1333 at net/core/dev.c:8638
rollback_registered_many+0x75d/0xda0
[ 182.002724][ T1333] Modules linked in: virt_wifi cfg80211 dummy veth
openvswitch nsh nf_conncount nf_nat nf_conntrack6
[ 182.002724][ T1333] CPU: 0 PID: 1333 Comm: ip Not tainted 5.3.0+ #370
[ 182.002724][ T1333] RIP: 0010:rollback_registered_many+0x75d/0xda0
[ 182.002724][ T1333] Code: 0c 00 00 48 89 de 4c 89 ff e8 6f 5a 04 00 48 89 df
e8 c7 26 fd ff 84 c0 0f 84 a5 fd ff ff 40
[ 182.002724][ T1333] RSP: 0018:ffff88810900f348 EFLAGS: 00010286
[ 182.002724][ T1333] RAX: 0000000000000024 RBX: ffff88811361d700 RCX:
0000000000000000
[ 182.002724][ T1333] RDX: 0000000000000024 RSI: 0000000000000008 RDI:
ffffed1021201e5f
[ 182.002724][ T1333] RBP: ffff88810900f4e0 R08: ffffed1022c3ff71 R09:
ffffed1022c3ff71
[ 182.002724][ T1333] R10: 0000000000000001 R11: ffffed1022c3ff70 R12:
dffffc0000000000
[ 182.002724][ T1333] R13: ffff88810900f460 R14: ffff88810900f420 R15:
ffff8881075f1940
[ 182.002724][ T1333] FS: 00007f77c42240c0(0000) GS:ffff888116000000(0000)
knlGS:0000000000000000
[ 182.002724][ T1333] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 182.002724][ T1333] CR2: 00007f77c3706240 CR3: 000000011139e000 CR4:
00000000001006f0
[ 182.002724][ T1333] Call Trace:
[ 182.002724][ T1333] ? generic_xdp_install+0x310/0x310
[ 182.002724][ T1333] ? check_chain_key+0x236/0x5d0
[ 182.002724][ T1333] ? __nla_validate_parse+0x98/0x1ad0
[ 182.002724][ T1333] unregister_netdevice_many.part.123+0x13/0x1b0
[ 182.002724][ T1333] rtnl_delete_link+0xbc/0x100
[ 182.002724][ T1333] ? rtnl_af_register+0xc0/0xc0
[ 182.002724][ T1333] rtnl_dellink+0x2e7/0x870
[ ... ]
[ 192.874736][ T1333] unregister_netdevice: waiting for dummy0 to become free.
Usage count = 1
This patch adds notifier routine to delete upper interface before deleting
lower interface.
Fixes: c7cdba31ed8b ("mac80211-next: rtnetlink wifi simulation device")
Signed-off-by: Taehee Yoo <ap420...@gmail.com>
---
v4:
- Add this new patch to fix refcnt leaks in the virt_wifi module
drivers/net/wireless/virt_wifi.c | 51 ++++++++++++++++++++++++++++++--
1 file changed, 49 insertions(+), 2 deletions(-)
diff --git a/drivers/net/wireless/virt_wifi.c b/drivers/net/wireless/virt_wifi.c
index be92e1220284..aadbacb01c8d 100644
--- a/drivers/net/wireless/virt_wifi.c
+++ b/drivers/net/wireless/virt_wifi.c
@@ -590,6 +590,42 @@ static struct rtnl_link_ops virt_wifi_link_ops = {
.priv_size = sizeof(struct virt_wifi_netdev_priv),
};
+static inline bool netif_is_virt_wifi_dev(const struct net_device *dev)
+{
+ return rcu_access_pointer(dev->rx_handler) == virt_wifi_rx_handler;
+}
+
+static int virt_wifi_event(struct notifier_block *this, unsigned long event,
+ void *ptr)
+{
+ struct net_device *lower_dev = netdev_notifier_info_to_dev(ptr);
+ struct virt_wifi_netdev_priv *priv;
+ struct net_device *upper_dev;
+ LIST_HEAD(list_kill);
+
+ if (!netif_is_virt_wifi_dev(lower_dev))
+ return NOTIFY_DONE;
+
+ switch (event) {
+ case NETDEV_UNREGISTER:
+ priv = rtnl_dereference(lower_dev->rx_handler_data);
+ if (!priv)
+ return NOTIFY_DONE;
+
+ upper_dev = priv->upperdev;
+
+ upper_dev->rtnl_link_ops->dellink(upper_dev, &list_kill);
+ unregister_netdevice_many(&list_kill);
+ break;
+ }
+
+ return NOTIFY_DONE;
+}
+
+static struct notifier_block virt_wifi_notifier = {
+ .notifier_call = virt_wifi_event,
+};
+
/* Acquires and releases the rtnl lock. */
static int __init virt_wifi_init_module(void)
{
@@ -598,14 +634,24 @@ static int __init virt_wifi_init_module(void)
/* Guaranteed to be locallly-administered and not multicast. */
eth_random_addr(fake_router_bssid);
+ err = register_netdevice_notifier(&virt_wifi_notifier);
+ if (err)
+ return err;
+
common_wiphy = virt_wifi_make_wiphy();
if (!common_wiphy)
- return -ENOMEM;
+ goto notifier;
err = rtnl_link_register(&virt_wifi_link_ops);
if (err)
- virt_wifi_destroy_wiphy(common_wiphy);
+ goto destroy_wiphy;
+ return 0;
+
+destroy_wiphy:
+ virt_wifi_destroy_wiphy(common_wiphy);
+notifier:
+ unregister_netdevice_notifier(&virt_wifi_notifier);
return err;
}
@@ -615,6 +661,7 @@ static void __exit virt_wifi_cleanup_module(void)
/* Will delete any devices that depend on the wiphy. */
rtnl_link_unregister(&virt_wifi_link_ops);
virt_wifi_destroy_wiphy(common_wiphy);
+ unregister_netdevice_notifier(&virt_wifi_notifier);
}
module_init(virt_wifi_init_module);
--
2.17.1
