From: Taehee Yoo ap420073@gmail.com
[ Upstream commit de0083c7ed7dba036d1ed6e012157649d45313c8 ]
When an interface is being deleted, "/proc/net/dev_snmp6/<interface name>" is deleted. The function for this is addrconf_ifdown() in the addrconf_notify() and it is called by notification, which is NETDEV_UNREGISTER. But, if NETDEV_CHANGEMTU is triggered after NETDEV_UNREGISTER, this proc file will be created again. This recreated proc file will be deleted by netdev_wati_allrefs(). Before netdev_wait_allrefs() is called, creating a new HSR interface routine can be executed and It tries to create a proc file but it will find an un-deleted proc file. At this point, it warns about it.
To avoid this situation, it can use ->dellink() instead of ->ndo_uninit() to release resources because ->dellink() is called before NETDEV_UNREGISTER. So, a proc file will not be recreated.
Test commands ip link add dummy0 type dummy ip link add dummy1 type dummy ip link set dummy0 mtu 1300
#SHELL1 while : do ip link add hsr0 type hsr slave1 dummy0 slave2 dummy1 done
#SHELL2 while : do ip link del hsr0 done
Splat looks like: [ 9888.980852][ T2752] proc_dir_entry 'dev_snmp6/hsr0' already registered [ 9888.981797][ C2] WARNING: CPU: 2 PID: 2752 at fs/proc/generic.c:372 proc_register+0x2d5/0x430 [ 9888.981798][ C2] Modules linked in: hsr dummy veth openvswitch nsh nf_conncount nf_nat nf_conntrack nf_defrag_ipv6x [ 9888.981814][ C2] CPU: 2 PID: 2752 Comm: ip Tainted: G W 5.8.0-rc1+ #616 [ 9888.981815][ C2] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006 [ 9888.981816][ C2] RIP: 0010:proc_register+0x2d5/0x430 [ 9888.981818][ C2] Code: fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 65 01 00 00 49 8b b5 e0 00 00 00 48 89 ea 40 [ 9888.981819][ C2] RSP: 0018:ffff8880628dedf0 EFLAGS: 00010286 [ 9888.981821][ C2] RAX: dffffc0000000008 RBX: ffff888028c69170 RCX: ffffffffaae09a62 [ 9888.981822][ C2] RDX: 0000000000000001 RSI: 0000000000000008 RDI: ffff88806c9f75ac [ 9888.981823][ C2] RBP: ffff888028c693f4 R08: ffffed100d9401bd R09: ffffed100d9401bd [ 9888.981824][ C2] R10: ffffffffaddf406f R11: 0000000000000001 R12: ffff888028c69308 [ 9888.981825][ C2] R13: ffff8880663584c8 R14: dffffc0000000000 R15: ffffed100518d27e [ 9888.981827][ C2] FS: 00007f3876b3b0c0(0000) GS:ffff88806c800000(0000) knlGS:0000000000000000 [ 9888.981828][ C2] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 9888.981829][ C2] CR2: 00007f387601a8c0 CR3: 000000004101a002 CR4: 00000000000606e0 [ 9888.981830][ C2] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 9888.981831][ C2] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 9888.981832][ C2] Call Trace: [ 9888.981833][ C2] ? snmp6_seq_show+0x180/0x180 [ 9888.981834][ C2] proc_create_single_data+0x7c/0xa0 [ 9888.981835][ C2] snmp6_register_dev+0xb0/0x130 [ 9888.981836][ C2] ipv6_add_dev+0x4b7/0xf60 [ 9888.981837][ C2] addrconf_notify+0x684/0x1ca0 [ 9888.981838][ C2] ? __mutex_unlock_slowpath+0xd0/0x670 [ 9888.981839][ C2] ? kasan_unpoison_shadow+0x30/0x40 [ 9888.981840][ C2] ? wait_for_completion+0x250/0x250 [ 9888.981841][ C2] ? inet6_ifinfo_notify+0x100/0x100 [ 9888.981842][ C2] ? dropmon_net_event+0x227/0x410 [ 9888.981843][ C2] ? notifier_call_chain+0x90/0x160 [ 9888.981844][ C2] ? inet6_ifinfo_notify+0x100/0x100 [ 9888.981845][ C2] notifier_call_chain+0x90/0x160 [ 9888.981846][ C2] register_netdevice+0xbe5/0x1070 [ ... ]
Reported-by: syzbot+1d51c8b74efa4c44adeb@syzkaller.appspotmail.com Fixes: e0a4b99773d3 ("hsr: use upper/lower device infrastructure") 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 --- net/hsr/hsr_device.c | 21 +-------------------- net/hsr/hsr_device.h | 2 +- net/hsr/hsr_main.c | 9 ++++++--- net/hsr/hsr_netlink.c | 17 +++++++++++++++++ 4 files changed, 25 insertions(+), 24 deletions(-)
diff --git a/net/hsr/hsr_device.c b/net/hsr/hsr_device.c index fc7027314ad80..ef100cfd2ac1b 100644 --- a/net/hsr/hsr_device.c +++ b/net/hsr/hsr_device.c @@ -341,7 +341,7 @@ static void hsr_announce(struct timer_list *t) rcu_read_unlock(); }
-static void hsr_del_ports(struct hsr_priv *hsr) +void hsr_del_ports(struct hsr_priv *hsr) { struct hsr_port *port;
@@ -358,31 +358,12 @@ static void hsr_del_ports(struct hsr_priv *hsr) hsr_del_port(port); }
-/* This has to be called after all the readers are gone. - * Otherwise we would have to check the return value of - * hsr_port_get_hsr(). - */ -static void hsr_dev_destroy(struct net_device *hsr_dev) -{ - struct hsr_priv *hsr = netdev_priv(hsr_dev); - - hsr_debugfs_term(hsr); - hsr_del_ports(hsr); - - del_timer_sync(&hsr->prune_timer); - del_timer_sync(&hsr->announce_timer); - - hsr_del_self_node(hsr); - hsr_del_nodes(&hsr->node_db); -} - static const struct net_device_ops hsr_device_ops = { .ndo_change_mtu = hsr_dev_change_mtu, .ndo_open = hsr_dev_open, .ndo_stop = hsr_dev_close, .ndo_start_xmit = hsr_dev_xmit, .ndo_fix_features = hsr_fix_features, - .ndo_uninit = hsr_dev_destroy, };
static struct device_type hsr_type = { diff --git a/net/hsr/hsr_device.h b/net/hsr/hsr_device.h index a099d7de7e790..b8f9262ed101a 100644 --- a/net/hsr/hsr_device.h +++ b/net/hsr/hsr_device.h @@ -11,6 +11,7 @@ #include <linux/netdevice.h> #include "hsr_main.h"
+void hsr_del_ports(struct hsr_priv *hsr); void hsr_dev_setup(struct net_device *dev); int hsr_dev_finalize(struct net_device *hsr_dev, struct net_device *slave[2], unsigned char multicast_spec, u8 protocol_version, @@ -18,5 +19,4 @@ int hsr_dev_finalize(struct net_device *hsr_dev, struct net_device *slave[2], void hsr_check_carrier_and_operstate(struct hsr_priv *hsr); bool is_hsr_master(struct net_device *dev); int hsr_get_max_mtu(struct hsr_priv *hsr); - #endif /* __HSR_DEVICE_H */ diff --git a/net/hsr/hsr_main.c b/net/hsr/hsr_main.c index e2564de676038..144da15f0a817 100644 --- a/net/hsr/hsr_main.c +++ b/net/hsr/hsr_main.c @@ -6,6 +6,7 @@ */
#include <linux/netdevice.h> +#include <net/rtnetlink.h> #include <linux/rculist.h> #include <linux/timer.h> #include <linux/etherdevice.h> @@ -100,8 +101,10 @@ static int hsr_netdev_notify(struct notifier_block *nb, unsigned long event, master = hsr_port_get_hsr(port->hsr, HSR_PT_MASTER); hsr_del_port(port); if (hsr_slave_empty(master->hsr)) { - unregister_netdevice_queue(master->dev, - &list_kill); + const struct rtnl_link_ops *ops; + + ops = master->dev->rtnl_link_ops; + ops->dellink(master->dev, &list_kill); unregister_netdevice_many(&list_kill); } } @@ -144,9 +147,9 @@ static int __init hsr_init(void)
static void __exit hsr_exit(void) { - unregister_netdevice_notifier(&hsr_nb); hsr_netlink_exit(); hsr_debugfs_remove_root(); + unregister_netdevice_notifier(&hsr_nb); }
module_init(hsr_init); diff --git a/net/hsr/hsr_netlink.c b/net/hsr/hsr_netlink.c index 1decb25f6764a..6e14b7d226399 100644 --- a/net/hsr/hsr_netlink.c +++ b/net/hsr/hsr_netlink.c @@ -83,6 +83,22 @@ static int hsr_newlink(struct net *src_net, struct net_device *dev, return hsr_dev_finalize(dev, link, multicast_spec, hsr_version, extack); }
+static void hsr_dellink(struct net_device *dev, struct list_head *head) +{ + struct hsr_priv *hsr = netdev_priv(dev); + + del_timer_sync(&hsr->prune_timer); + del_timer_sync(&hsr->announce_timer); + + hsr_debugfs_term(hsr); + hsr_del_ports(hsr); + + hsr_del_self_node(hsr); + hsr_del_nodes(&hsr->node_db); + + unregister_netdevice_queue(dev, head); +} + static int hsr_fill_info(struct sk_buff *skb, const struct net_device *dev) { struct hsr_priv *hsr = netdev_priv(dev); @@ -118,6 +134,7 @@ static struct rtnl_link_ops hsr_link_ops __read_mostly = { .priv_size = sizeof(struct hsr_priv), .setup = hsr_dev_setup, .newlink = hsr_newlink, + .dellink = hsr_dellink, .fill_info = hsr_fill_info, };