| Message ID | 20190928164843.31800-13-ap420073@gmail.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Delegated to: | Kalle Valo |
| Headers | show |
| Series | net: fix nested device bugs | expand |
On Sat, 2019-09-28 at 16:48 +0000, Taehee Yoo wrote: > virt_wifi_newlink() calls netdev_upper_dev_link() and it internally > holds reference count of lower interface. [...] > This patch adds notifier routine to delete upper interface before deleting > lower interface. Good catch, thanks! For now I'll assume this will go in through net together with the whole series (once ready), shout if you want something else. johannes
2019-09-28, 16:48:43 +0000, Taehee Yoo wrote: > 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 There should also be "ip link del dummy0" in this reproducer, right? [...] > @@ -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; > + Here err is 0. > common_wiphy = virt_wifi_make_wiphy(); > if (!common_wiphy) > - return -ENOMEM; > + goto notifier; err is still 0 when we jump... > 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; > } ... so now we return 0 on failure. Can you add an "err = -ENOMEM" before "common_wiphy = ..."? Thanks.
On Mon, 7 Oct 2019 at 20:22, Sabrina Dubroca <sd@queasysnail.net> wrote: > Hi Sabrina, Thank you for the review! > 2019-09-28, 16:48:43 +0000, Taehee Yoo wrote: > > 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 > > There should also be "ip link del dummy0" in this reproducer, right? > > [...] > > > @@ -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; > > + > > Here err is 0. > > > common_wiphy = virt_wifi_make_wiphy(); > > if (!common_wiphy) > > - return -ENOMEM; > > + goto notifier; > > err is still 0 when we jump... > > > 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; > > } > > ... so now we return 0 on failure. Can you add an "err = -ENOMEM" > before "common_wiphy = ..."? > You're right, I will fix this in a v5 patch! Thanks! > Thanks. > > -- > Sabrina
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);
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 <ap420073@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(-)