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hsr: switch ->dellink() to ->ndo_uninit() 

Switching from ->priv_destructor to dellink() has an unexpected
consequence: existing RCU readers, that is, hsr_port_get_hsr()
callers, may still be able to read the port list.

Instead of checking the return value of each hsr_port_get_hsr(),
we can just move it to ->ndo_uninit() which is called after
device unregister and synchronize_net(), and we still have RTNL
lock there.

Fixes: b9a1e62740 ("hsr: implement dellink to clean up resources")
Fixes: edf070a0fb ("hsr: fix a NULL pointer deref in hsr_dev_xmit()")
Reported-by: syzbot+097ef84cdc95843fbaa8@syzkaller.appspotmail.com
Cc: Arvid Brodin <arvid.brodin@alten.se>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Cong Wang 2019-07-09 23:24:54 -07:00 committed by David S. Miller
parent aa4c0c9091
commit 311633b604
3 changed files with 8 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
net/hsr/hsr_device.c
View File

@ -227,13 +227,8 @@ static int hsr_dev_xmit(struct sk_buff *skb, struct net_device *dev)
struct hsr_port *master;
master = hsr_port_get_hsr(hsr, HSR_PT_MASTER);
if (master) {
skb->dev = master->dev;
hsr_forward_skb(skb, master);
} else {
atomic_long_inc(&dev->tx_dropped);
dev_kfree_skb_any(skb);
}
return NETDEV_TX_OK;
}
@ -348,7 +343,11 @@ static void hsr_announce(struct timer_list *t)
rcu_read_unlock();
}
void hsr_dev_destroy(struct net_device *hsr_dev)
/* 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;
struct hsr_port *port;
@ -364,8 +363,6 @@ void hsr_dev_destroy(struct net_device *hsr_dev)
del_timer_sync(&hsr->prune_timer);
del_timer_sync(&hsr->announce_timer);
synchronize_rcu();
hsr_del_self_node(&hsr->self_node_db);
hsr_del_nodes(&hsr->node_db);
}
@ -376,6 +373,7 @@ static const struct net_device_ops hsr_device_ops = {
.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 = {

1
net/hsr/hsr_device.h
View File

@ -14,7 +14,6 @@
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);
void hsr_dev_destroy(struct net_device *hsr_dev);
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);

7
net/hsr/hsr_netlink.c
View File

@ -69,12 +69,6 @@ static int hsr_newlink(struct net *src_net, struct net_device *dev,
return hsr_dev_finalize(dev, link, multicast_spec, hsr_version);
}
static void hsr_dellink(struct net_device *hsr_dev, struct list_head *head)
{
hsr_dev_destroy(hsr_dev);
unregister_netdevice_queue(hsr_dev, head);
}
static int hsr_fill_info(struct sk_buff *skb, const struct net_device *dev)
{
struct hsr_priv *hsr;
@ -119,7 +113,6 @@ 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,
};