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Date: Mon, 21 Oct 2019 18:47:59 +0000
From: Taehee Yoo <ap420073@...il.com>
To: davem@...emloft.net, netdev@...r.kernel.org,
linux-wireless@...r.kernel.org, jakub.kicinski@...ronome.com,
johannes@...solutions.net, j.vosburgh@...il.com, vfalico@...il.com,
andy@...yhouse.net, jiri@...nulli.us, sd@...asysnail.net,
roopa@...ulusnetworks.com, saeedm@...lanox.com,
manishc@...vell.com, rahulv@...vell.com, kys@...rosoft.com,
haiyangz@...rosoft.com, stephen@...workplumber.org,
sashal@...nel.org, hare@...e.de, varun@...lsio.com,
ubraun@...ux.ibm.com, kgraul@...ux.ibm.com,
jay.vosburgh@...onical.com, schuffelen@...gle.com, bjorn@...k.no
Cc: ap420073@...il.com
Subject: [PATCH net v5 10/10] virt_wifi: fix refcnt leak in module exit routine
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@...il.com>
---
v4 -> v5 :
- Log message update
- Fix wrong error value in error path of __init routine
- hold module refcnt when interface is created
v4 :
- Initial patch
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 be92e1220284..ed80ce91231f 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 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 +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);
--
2.17.1
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