Date: Thu, 09 Nov 2023 22:26:13 +0200
From: Jay Vosburgh <jay.vosburgh@...onical.com>
To: Eric Dumazet <edumazet@...gle.com>
cc: "David S . Miller" <davem@...emloft.net>,
    Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
    Andy Gospodarek <andy@...yhouse.net>, netdev@...r.kernel.org,
    eric.dumazet@...il.com, syzbot <syzkaller@...glegroups.com>
Subject: Re: [PATCH net] bonding: stop the device in bond_setup_by_slave()

Eric Dumazet <edumazet@...gle.com> wrote:

>Commit 9eed321cde22 ("net: lapbether: only support ethernet devices")
>has been able to keep syzbot away from net/lapb, until today.
>
>In the following splat [1], the issue is that a lapbether device has
>been created on a bonding device without members. Then adding a non
>ARPHRD_ETHER member forced the bonding master to change its type.
>
>The fix is to make sure we call dev_close() in bond_setup_by_slave()
>so that the potential linked lapbether devices (or any other devices
>having assumptions on the physical device) are removed.
>
>A similar bug has been addressed in commit 40baec225765
>("bonding: fix panic on non-ARPHRD_ETHER enslave failure")
>
>[1]
>skbuff: skb_under_panic: text:ffff800089508810 len:44 put:40 head:ffff0000c78e7c00 data:ffff0000c78e7bea tail:0x16 end:0x140 dev:bond0
>kernel BUG at net/core/skbuff.c:192 !
>Internal error: Oops - BUG: 00000000f2000800 [#1] PREEMPT SMP
>Modules linked in:
>CPU: 0 PID: 6007 Comm: syz-executor383 Not tainted 6.6.0-rc3-syzkaller-gbf6547d8715b #0
>Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/04/2023
>pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
>pc : skb_panic net/core/skbuff.c:188 [inline]
>pc : skb_under_panic+0x13c/0x140 net/core/skbuff.c:202
>lr : skb_panic net/core/skbuff.c:188 [inline]
>lr : skb_under_panic+0x13c/0x140 net/core/skbuff.c:202
>sp : ffff800096a06aa0
>x29: ffff800096a06ab0 x28: ffff800096a06ba0 x27: dfff800000000000
>x26: ffff0000ce9b9b50 x25: 0000000000000016 x24: ffff0000c78e7bea
>x23: ffff0000c78e7c00 x22: 000000000000002c x21: 0000000000000140
>x20: 0000000000000028 x19: ffff800089508810 x18: ffff800096a06100
>x17: 0000000000000000 x16: ffff80008a629a3c x15: 0000000000000001
>x14: 1fffe00036837a32 x13: 0000000000000000 x12: 0000000000000000
>x11: 0000000000000201 x10: 0000000000000000 x9 : cb50b496c519aa00
>x8 : cb50b496c519aa00 x7 : 0000000000000001 x6 : 0000000000000001
>x5 : ffff800096a063b8 x4 : ffff80008e280f80 x3 : ffff8000805ad11c
>x2 : 0000000000000001 x1 : 0000000100000201 x0 : 0000000000000086
>Call trace:
>skb_panic net/core/skbuff.c:188 [inline]
>skb_under_panic+0x13c/0x140 net/core/skbuff.c:202
>skb_push+0xf0/0x108 net/core/skbuff.c:2446
>ip6gre_header+0xbc/0x738 net/ipv6/ip6_gre.c:1384
>dev_hard_header include/linux/netdevice.h:3136 [inline]
>lapbeth_data_transmit+0x1c4/0x298 drivers/net/wan/lapbether.c:257
>lapb_data_transmit+0x8c/0xb0 net/lapb/lapb_iface.c:447
>lapb_transmit_buffer+0x178/0x204 net/lapb/lapb_out.c:149
>lapb_send_control+0x220/0x320 net/lapb/lapb_subr.c:251
>__lapb_disconnect_request+0x9c/0x17c net/lapb/lapb_iface.c:326
>lapb_device_event+0x288/0x4e0 net/lapb/lapb_iface.c:492
>notifier_call_chain+0x1a4/0x510 kernel/notifier.c:93
>raw_notifier_call_chain+0x3c/0x50 kernel/notifier.c:461
>call_netdevice_notifiers_info net/core/dev.c:1970 [inline]
>call_netdevice_notifiers_extack net/core/dev.c:2008 [inline]
>call_netdevice_notifiers net/core/dev.c:2022 [inline]
>__dev_close_many+0x1b8/0x3c4 net/core/dev.c:1508
>dev_close_many+0x1e0/0x470 net/core/dev.c:1559
>dev_close+0x174/0x250 net/core/dev.c:1585
>lapbeth_device_event+0x2e4/0x958 drivers/net/wan/lapbether.c:466
>notifier_call_chain+0x1a4/0x510 kernel/notifier.c:93
>raw_notifier_call_chain+0x3c/0x50 kernel/notifier.c:461
>call_netdevice_notifiers_info net/core/dev.c:1970 [inline]
>call_netdevice_notifiers_extack net/core/dev.c:2008 [inline]
>call_netdevice_notifiers net/core/dev.c:2022 [inline]
>__dev_close_many+0x1b8/0x3c4 net/core/dev.c:1508
>dev_close_many+0x1e0/0x470 net/core/dev.c:1559
>dev_close+0x174/0x250 net/core/dev.c:1585
>bond_enslave+0x2298/0x30cc drivers/net/bonding/bond_main.c:2332
>bond_do_ioctl+0x268/0xc64 drivers/net/bonding/bond_main.c:4539
>dev_ifsioc+0x754/0x9ac
>dev_ioctl+0x4d8/0xd34 net/core/dev_ioctl.c:786
>sock_do_ioctl+0x1d4/0x2d0 net/socket.c:1217
>sock_ioctl+0x4e8/0x834 net/socket.c:1322
>vfs_ioctl fs/ioctl.c:51 [inline]
>__do_sys_ioctl fs/ioctl.c:871 [inline]
>__se_sys_ioctl fs/ioctl.c:857 [inline]
>__arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:857
>__invoke_syscall arch/arm64/kernel/syscall.c:37 [inline]
>invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:51
>el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:136
>do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:155
>el0_svc+0x58/0x16c arch/arm64/kernel/entry-common.c:678
>el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:696
>el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:591
>Code: aa1803e6 aa1903e7 a90023f5 94785b8b (d4210000)
>
>Fixes: 872254dd6b1f ("net/bonding: Enable bonding to enslave non ARPHRD_ETHER")
>Reported-by: syzbot <syzkaller@...glegroups.com>
>Signed-off-by: Eric Dumazet <edumazet@...gle.com>

	I was initially worred that the close / open dance was on the
regular path, but it's only for the non-ARPHRD_ETHER case.  That's
really for Infiniband IPoIB, and I'm not sure that there is anything
that can be stacked atop an IPoIB bond.

Acked-by: Jay Vosburgh <jay.vosburgh@...onical.com>

	-J

>---
> drivers/net/bonding/bond_main.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
>diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
>index 51d47eda1c873debda6da094377bcb3367a78f6e..8e6cc0e133b7f19afccd3ecf44bea5ceacb393b1 100644
>--- a/drivers/net/bonding/bond_main.c
>+++ b/drivers/net/bonding/bond_main.c
>@@ -1500,6 +1500,10 @@ static void bond_compute_features(struct bonding *bond)
> static void bond_setup_by_slave(struct net_device *bond_dev,
> 				struct net_device *slave_dev)
> {
>+	bool was_up = !!(bond_dev->flags & IFF_UP);
>+
>+	dev_close(bond_dev);
>+
> 	bond_dev->header_ops	    = slave_dev->header_ops;
> 
> 	bond_dev->type		    = slave_dev->type;
>@@ -1514,6 +1518,8 @@ static void bond_setup_by_slave(struct net_device *bond_dev,
> 		bond_dev->flags &= ~(IFF_BROADCAST | IFF_MULTICAST);
> 		bond_dev->flags |= (IFF_POINTOPOINT | IFF_NOARP);
> 	}
>+	if (was_up)
>+		dev_open(bond_dev, NULL);
> }
> 
> /* On bonding slaves other than the currently active slave, suppress
>-- 
>2.42.0.869.gea05f2083d-goog

---
	-Jay Vosburgh, jay.vosburgh@...onical.com

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