Messages in this thread | | | Date | Mon, 13 Mar 2023 18:35:08 +0900 | From | Shigeru Yoshida <> | Subject | Re: [PATCH net] bonding: Fix warning in default_device_exit_batch() |
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Hi Nik,
On Sun, Mar 12, 2023 at 10:58:18PM +0200, Nikolay Aleksandrov wrote: > On 12/03/2023 17:21, Shigeru Yoshida wrote: > > syzbot reported warning in default_device_exit_batch() like below [1]: > > > > WARNING: CPU: 1 PID: 56 at net/core/dev.c:10867 unregister_netdevice_many_notify+0x14cf/0x19f0 net/core/dev.c:10867 > > ... > > Call Trace: > > <TASK> > > unregister_netdevice_many net/core/dev.c:10897 [inline] > > default_device_exit_batch+0x451/0x5b0 net/core/dev.c:11350 > > ops_exit_list+0x125/0x170 net/core/net_namespace.c:174 > > cleanup_net+0x4ee/0xb10 net/core/net_namespace.c:613 > > process_one_work+0x9bf/0x1820 kernel/workqueue.c:2390 > > worker_thread+0x669/0x1090 kernel/workqueue.c:2537 > > kthread+0x2e8/0x3a0 kernel/kthread.c:376 > > ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308 > > </TASK> > > > > For bond devices which also has a master device, IFF_SLAVE flag is > > cleared at err_undo_flags label in bond_enslave() if it is not > > ARPHRD_ETHER type. In this case, __bond_release_one() is not called > > when bond_netdev_event() received NETDEV_UNREGISTER event. This > > causes the above warning. > > > > This patch fixes this issue by setting IFF_SLAVE flag at > > err_undo_flags label in bond_enslave() if the bond device has a master > > device. > > > > The proper way is to check if the bond device had the IFF_SLAVE flag before the > ether_setup() call which clears it, and restore it after. > > > Fixes: 7d5cd2ce5292 ("bonding: correctly handle bonding type change on enslave failure") > > Cc: Nikolay Aleksandrov <nikolay@cumulusnetworks.com> > > Link: https://syzkaller.appspot.com/bug?id=391c7b1f6522182899efba27d891f1743e8eb3ef [1] > > Reported-by: syzbot+9dfc3f3348729cc82277@syzkaller.appspotmail.com > > Signed-off-by: Shigeru Yoshida <syoshida@redhat.com> > > --- > > drivers/net/bonding/bond_main.c | 2 ++ > > include/net/bonding.h | 5 +++++ > > 2 files changed, 7 insertions(+) > > > > diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c > > index 00646aa315c3..1a8b59e1468d 100644 > > --- a/drivers/net/bonding/bond_main.c > > +++ b/drivers/net/bonding/bond_main.c > > @@ -2291,6 +2291,8 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev, > > dev_close(bond_dev); > > ether_setup(bond_dev); > > bond_dev->flags |= IFF_MASTER; > > + if (bond_has_master(bond)) > > + bond_dev->flags |= IFF_SLAVE; > > bond_dev->priv_flags &= ~IFF_TX_SKB_SHARING; > > } > > } > > diff --git a/include/net/bonding.h b/include/net/bonding.h > > index ea36ab7f9e72..ed0b49501fad 100644 > > --- a/include/net/bonding.h > > +++ b/include/net/bonding.h > > @@ -57,6 +57,11 @@ > > > > #define bond_has_slaves(bond) !list_empty(bond_slave_list(bond)) > > > > +/* master list primitives */ > > +#define bond_master_list(bond) (&(bond)->dev->adj_list.upper) > > + > > +#define bond_has_master(bond) !list_empty(bond_master_list(bond)) > > + > > This is not the proper way to check for a master device. > > > /* IMPORTANT: bond_first/last_slave can return NULL in case of an empty list */ > > #define bond_first_slave(bond) \ > > (bond_has_slaves(bond) ? \ > > The device flags are wrong because of ether_setup() which clears IFF_SLAVE, we should > just check if it was present before and restore it after the ether_setup() call.
Thank you so much for your comment! I understand your point, and agree that your approach must resolve the issue.
BTW, do you mean there is a case where a device has IFF_SLAVE flag but the upper list is empty? I thought a device with IFF_SLAVE flag has a master device in the upper list (that is why I took the above way.)
Thanks, Shigeru
> > I'll send a fix tomorrow after testing it. > > Thanks, > Nik >
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