From: Jakub Kicinski kuba@kernel.org
commit 766b0515d5bec4b780750773ed3009b148df8c0a upstream.
If register_netdevice() fails at the very last stage - the notifier call - some subsystems may have already seen it and grabbed a reference. struct net_device can't be freed right away without calling netdev_wait_all_refs().
Now that we have a clean interface in form of dev->needs_free_netdev and lenient free_netdev() we can undo what commit 93ee31f14f6f ("[NET]: Fix free_netdev on register_netdev failure.") has done and complete the unregistration path by bringing the net_set_todo() call back.
After registration fails user is still expected to explicitly free the net_device, so make sure ->needs_free_netdev is cleared, otherwise rolling back the registration will cause the old double free for callers who release rtnl_lock before the free.
This also solves the problem of priv_destructor not being called on notifier error.
net_set_todo() will be moved back into unregister_netdevice_queue() in a follow up.
Reported-by: Hulk Robot hulkci@huawei.com Reported-by: Yang Yingliang yangyingliang@huawei.com Signed-off-by: Jakub Kicinski kuba@kernel.org --- net/core/dev.c | 14 ++++---------- 1 file changed, 4 insertions(+), 10 deletions(-)
diff --git a/net/core/dev.c b/net/core/dev.c index adde93cbca9f..0071a11a6dc3 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -10077,17 +10077,11 @@ int register_netdevice(struct net_device *dev) ret = call_netdevice_notifiers(NETDEV_REGISTER, dev); ret = notifier_to_errno(ret); if (ret) { + /* Expect explicit free_netdev() on failure */ + dev->needs_free_netdev = false; rollback_registered(dev); - rcu_barrier(); - - dev->reg_state = NETREG_UNREGISTERED; - /* We should put the kobject that hold in - * netdev_unregister_kobject(), otherwise - * the net device cannot be freed when - * driver calls free_netdev(), because the - * kobject is being hold. - */ - kobject_put(&dev->dev.kobj); + net_set_todo(dev); + goto out; } /* * Prevent userspace races by waiting until the network