From: Taehee Yoo ap420073@gmail.com
[ Upstream commit 1962f86b42ed06ea6af9ff09390243b99d9eb83a ]
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 ip link del dummy0
Splat looks like: [ 133.787526][ T788] WARNING: CPU: 1 PID: 788 at net/core/dev.c:8274 rollback_registered_many+0x835/0xc80 [ 133.788355][ T788] Modules linked in: virt_wifi cfg80211 dummy team af_packet sch_fq_codel ip_tables x_tables unix [ 133.789377][ T788] CPU: 1 PID: 788 Comm: ip Not tainted 5.4.0-rc3+ #96 [ 133.790069][ T788] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006 [ 133.791167][ T788] RIP: 0010:rollback_registered_many+0x835/0xc80 [ 133.791906][ T788] Code: 00 4d 85 ff 0f 84 b5 fd ff ff ba c0 0c 00 00 48 89 de 4c 89 ff e8 9b 58 04 00 48 89 df e8 30 [ 133.794317][ T788] RSP: 0018:ffff88805ba3f338 EFLAGS: 00010202 [ 133.795080][ T788] RAX: ffff88805e57e801 RBX: ffff88805ba34000 RCX: ffffffffa9294723 [ 133.796045][ T788] RDX: 1ffff1100b746816 RSI: 0000000000000008 RDI: ffffffffabcc4240 [ 133.797006][ T788] RBP: ffff88805ba3f4c0 R08: fffffbfff5798849 R09: fffffbfff5798849 [ 133.797993][ T788] R10: 0000000000000001 R11: fffffbfff5798848 R12: dffffc0000000000 [ 133.802514][ T788] R13: ffff88805ba3f440 R14: ffff88805ba3f400 R15: ffff88805ed622c0 [ 133.803237][ T788] FS: 00007f2e9608c0c0(0000) GS:ffff88806cc00000(0000) knlGS:0000000000000000 [ 133.804002][ T788] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 133.804664][ T788] CR2: 00007f2e95610603 CR3: 000000005f68c004 CR4: 00000000000606e0 [ 133.805363][ T788] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 133.806073][ T788] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 133.806787][ T788] Call Trace: [ 133.807069][ T788] ? generic_xdp_install+0x310/0x310 [ 133.807612][ T788] ? lock_acquire+0x164/0x3b0 [ 133.808077][ T788] ? is_bpf_text_address+0x5/0xf0 [ 133.808640][ T788] ? deref_stack_reg+0x9c/0xd0 [ 133.809138][ T788] ? __nla_validate_parse+0x98/0x1ab0 [ 133.809944][ T788] unregister_netdevice_many.part.122+0x13/0x1b0 [ 133.810599][ T788] rtnl_delete_link+0xbc/0x100 [ 133.811073][ T788] ? rtnl_af_register+0xc0/0xc0 [ 133.811672][ T788] rtnl_dellink+0x30e/0x8a0 [ 133.812205][ T788] ? is_bpf_text_address+0x5/0xf0 [ ... ]
[ 144.110530][ T788] 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 ap420073@gmail.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/wireless/virt_wifi.c | 54 ++++++++++++++++++++++++++++++-- 1 file changed, 52 insertions(+), 2 deletions(-)
diff --git a/drivers/net/wireless/virt_wifi.c b/drivers/net/wireless/virt_wifi.c index be92e1220284c..7997cc6de334f 100644 --- a/drivers/net/wireless/virt_wifi.c +++ b/drivers/net/wireless/virt_wifi.c @@ -548,6 +548,7 @@ static int virt_wifi_newlink(struct net *src_net, struct net_device *dev, priv->is_connected = false; priv->is_up = false; INIT_DELAYED_WORK(&priv->connect, virt_wifi_connect_complete); + __module_get(THIS_MODULE);
return 0; unregister_netdev: @@ -578,6 +579,7 @@ static void virt_wifi_dellink(struct net_device *dev, netdev_upper_dev_unlink(priv->lowerdev, dev);
unregister_netdevice_queue(dev, head); + module_put(THIS_MODULE);
/* Deleting the wiphy is handled in the module destructor. */ } @@ -590,6 +592,42 @@ static struct rtnl_link_ops virt_wifi_link_ops = { .priv_size = sizeof(struct virt_wifi_netdev_priv), };
+static 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 +636,25 @@ 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; + + err = -ENOMEM; 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 +664,7 @@ 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);