Re: [PATCH net] ip6mr: fix notification device destruction
From: Andrey Konovalov
Date: Fri Apr 21 2017 - 14:47:09 EST
On Fri, Apr 21, 2017 at 8:30 PM, Nikolay Aleksandrov
<nikolay@xxxxxxxxxxxxxxxxxxx> wrote:
> On 21/04/17 20:42, Nikolay Aleksandrov wrote:
>> Andrey Konovalov reported a BUG caused by the ip6mr code which is caused
>> because we call unregister_netdevice_many for a device that is already
>> being destroyed. In IPv4's ipmr that has been resolved by two commits
>> long time ago by introducing the "notify" parameter to the delete
>> function and avoiding the unregister when called from a notifier, so
>> let's do the same for ip6mr.
Hi Nikolay,
Your patch fixes BUG_ON() being triggered for me.
Tested-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Thanks!
>>
>> The trace from Andrey:
>> ------------[ cut here ]------------
>> kernel BUG at net/core/dev.c:6813!
>> invalid opcode: 0000 [#1] SMP KASAN
>> Modules linked in:
>> CPU: 1 PID: 1165 Comm: kworker/u4:3 Not tainted 4.11.0-rc7+ #251
>> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs
>> 01/01/2011
>> Workqueue: netns cleanup_net
>> task: ffff880069208000 task.stack: ffff8800692d8000
>> RIP: 0010:rollback_registered_many+0x348/0xeb0 net/core/dev.c:6813
>> RSP: 0018:ffff8800692de7f0 EFLAGS: 00010297
>> RAX: ffff880069208000 RBX: 0000000000000002 RCX: 0000000000000001
>> RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88006af90569
>> RBP: ffff8800692de9f0 R08: ffff8800692dec60 R09: 0000000000000000
>> R10: 0000000000000006 R11: 0000000000000000 R12: ffff88006af90070
>> R13: ffff8800692debf0 R14: dffffc0000000000 R15: ffff88006af90000
>> FS: 0000000000000000(0000) GS:ffff88006cb00000(0000)
>> knlGS:0000000000000000
>> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> CR2: 00007fe7e897d870 CR3: 00000000657e7000 CR4: 00000000000006e0
>> Call Trace:
>> unregister_netdevice_many.part.105+0x87/0x440 net/core/dev.c:7881
>> unregister_netdevice_many+0xc8/0x120 net/core/dev.c:7880
>> ip6mr_device_event+0x362/0x3f0 net/ipv6/ip6mr.c:1346
>> notifier_call_chain+0x145/0x2f0 kernel/notifier.c:93
>> __raw_notifier_call_chain kernel/notifier.c:394
>> raw_notifier_call_chain+0x2d/0x40 kernel/notifier.c:401
>> call_netdevice_notifiers_info+0x51/0x90 net/core/dev.c:1647
>> call_netdevice_notifiers net/core/dev.c:1663
>> rollback_registered_many+0x919/0xeb0 net/core/dev.c:6841
>> unregister_netdevice_many.part.105+0x87/0x440 net/core/dev.c:7881
>> unregister_netdevice_many net/core/dev.c:7880
>> default_device_exit_batch+0x4fa/0x640 net/core/dev.c:8333
>> ops_exit_list.isra.4+0x100/0x150 net/core/net_namespace.c:144
>> cleanup_net+0x5a8/0xb40 net/core/net_namespace.c:463
>> process_one_work+0xc04/0x1c10 kernel/workqueue.c:2097
>> worker_thread+0x223/0x19c0 kernel/workqueue.c:2231
>> kthread+0x35e/0x430 kernel/kthread.c:231
>> ret_from_fork+0x31/0x40 arch/x86/entry/entry_64.S:430
>> Code: 3c 32 00 0f 85 70 0b 00 00 48 b8 00 02 00 00 00 00 ad de 49 89
>> 47 78 e9 93 fe ff ff 49 8d 57 70 49 8d 5f 78 eb 9e e8 88 7a 14 fe <0f>
>> 0b 48 8b 9d 28 fe ff ff e8 7a 7a 14 fe 48 b8 00 00 00 00 00
>> RIP: rollback_registered_many+0x348/0xeb0 RSP: ffff8800692de7f0
>> ---[ end trace e0b29c57e9b3292c ]---
>>
>> Reported-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
>> Signed-off-by: Nikolay Aleksandrov <nikolay@xxxxxxxxxxxxxxxxxxx>
>> ---
>
> +CC LKML and Linus
>
>> Andrey could you please test with this patch applied ?
>> I have run the reproducer locally and can no longer trigger the bug.
>> I've made "notify" an int instead of a bool only to be closer to the ipmr
>> code for easier future patches.
>>
>> net/ipv6/ip6mr.c | 13 ++++++-------
>> 1 file changed, 6 insertions(+), 7 deletions(-)
>>
>> diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c
>> index fb4546e80c82..374997d26488 100644
>> --- a/net/ipv6/ip6mr.c
>> +++ b/net/ipv6/ip6mr.c
>> @@ -774,7 +774,8 @@ static struct net_device *ip6mr_reg_vif(struct net *net, struct mr6_table *mrt)
>> * Delete a VIF entry
>> */
>>
>> -static int mif6_delete(struct mr6_table *mrt, int vifi, struct list_head *head)
>> +static int mif6_delete(struct mr6_table *mrt, int vifi, int notify,
>> + struct list_head *head)
>> {
>> struct mif_device *v;
>> struct net_device *dev;
>> @@ -820,7 +821,7 @@ static int mif6_delete(struct mr6_table *mrt, int vifi, struct list_head *head)
>> dev->ifindex, &in6_dev->cnf);
>> }
>>
>> - if (v->flags & MIFF_REGISTER)
>> + if ((v->flags & MIFF_REGISTER) && !notify)
>> unregister_netdevice_queue(dev, head);
>>
>> dev_put(dev);
>> @@ -1331,7 +1332,6 @@ static int ip6mr_device_event(struct notifier_block *this,
>> struct mr6_table *mrt;
>> struct mif_device *v;
>> int ct;
>> - LIST_HEAD(list);
>>
>> if (event != NETDEV_UNREGISTER)
>> return NOTIFY_DONE;
>> @@ -1340,10 +1340,9 @@ static int ip6mr_device_event(struct notifier_block *this,
>> v = &mrt->vif6_table[0];
>> for (ct = 0; ct < mrt->maxvif; ct++, v++) {
>> if (v->dev == dev)
>> - mif6_delete(mrt, ct, &list);
>> + mif6_delete(mrt, ct, 1, NULL);
>> }
>> }
>> - unregister_netdevice_many(&list);
>>
>> return NOTIFY_DONE;
>> }
>> @@ -1552,7 +1551,7 @@ static void mroute_clean_tables(struct mr6_table *mrt, bool all)
>> for (i = 0; i < mrt->maxvif; i++) {
>> if (!all && (mrt->vif6_table[i].flags & VIFF_STATIC))
>> continue;
>> - mif6_delete(mrt, i, &list);
>> + mif6_delete(mrt, i, 0, &list);
>> }
>> unregister_netdevice_many(&list);
>>
>> @@ -1708,7 +1707,7 @@ int ip6_mroute_setsockopt(struct sock *sk, int optname, char __user *optval, uns
>> if (copy_from_user(&mifi, optval, sizeof(mifi_t)))
>> return -EFAULT;
>> rtnl_lock();
>> - ret = mif6_delete(mrt, mifi, NULL);
>> + ret = mif6_delete(mrt, mifi, 0, NULL);
>> rtnl_unlock();
>> return ret;
>>
>>
>
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