Commit 9eed321c ("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 40baec22
("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: 872254dd ("net/bonding: Enable bonding to enslave non ARPHRD_ETHER")
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Jay Vosburgh <jay.vosburgh@canonical.com>
Reviewed-by: Hangbin Liu <liuhangbin@gmail.com>
Link: https://lore.kernel.org/r/20231109180102.4085183-1-edumazet@google.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>