Re: [syzbot] BUG: MAX_LOCKDEP_KEYS too low! (2)

[Dmitry Vyukov]

On Tue, 8 Nov 2022 at 05:40, syzbot
<syzbot+a70a6358abd2c3f9550f@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> syzbot has found a reproducer for the following issue on:
>
> HEAD commit:    3577a7611842 Merge branches 'for-next/acpi', 'for-next/kbu..
> git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
> console output: https://syzkaller.appspot.com/x/log.txt?x=15ea3e61880000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=606e57fd25c5c6cc
> dashboard link: https://syzkaller.appspot.com/bug?extid=a70a6358abd2c3f9550f
> compiler:       Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, GNU ld (GNU Binutils for Debian) 2.35.2
> userspace arch: arm64
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=168c4c99880000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=145d6376880000
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/054b1f56af52/disk-3577a761.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/c616835b2a22/vmlinux-3577a761.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/9825c28b2090/Image-3577a761.gz.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+a70a6358abd2c3f9550f@xxxxxxxxxxxxxxxxxxxxxxxxx


I see team device code uses lockdep_register_key()/lockdep_set_class()
in some interesting ways:

https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git/tree/drivers/net/team/team.c?id=3577a76118426e4409ecf4f75520925eff67d42c#n1657
https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git/tree/drivers/net/team/team.c?id=3577a76118426e4409ecf4f75520925eff67d42c#n2008

I guess that's what causes lockdep capacity exhaustion. Does team use
it incorrectly?


> netlink: 4 bytes leftover after parsing attributes in process `syz-executor357'.
> device team6635 entered promiscuous mode
> 8021q: adding VLAN 0 to HW filter on device team6635
> BUG: MAX_LOCKDEP_KEYS too low!
> turning off the locking correctness validator.
> CPU: 0 PID: 9692 Comm: syz-executor357 Not tainted 6.1.0-rc4-syzkaller-31844-g3577a7611842 #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/30/2022
> Call trace:
>  dump_backtrace+0x1c4/0x1f0 arch/arm64/kernel/stacktrace.c:156
>  show_stack+0x2c/0x54 arch/arm64/kernel/stacktrace.c:163
>  __dump_stack lib/dump_stack.c:88 [inline]
>  dump_stack_lvl+0x104/0x16c lib/dump_stack.c:106
>  dump_stack+0x1c/0x58 lib/dump_stack.c:113
>  register_lock_class+0x2e4/0x2f8 kernel/locking/lockdep.c:1326
>  __lock_acquire+0xa8/0x3084 kernel/locking/lockdep.c:4934
>  lock_acquire+0x100/0x1f8 kernel/locking/lockdep.c:5668
>  __mutex_lock_common+0xd4/0xca8 kernel/locking/mutex.c:603
>  __mutex_lock kernel/locking/mutex.c:747 [inline]
>  mutex_lock_nested+0x38/0x44 kernel/locking/mutex.c:799
>  team_vlan_rx_add_vid+0x38/0xd8 drivers/net/team/team.c:1904
>  vlan_add_rx_filter_info net/8021q/vlan_core.c:211 [inline]
>  __vlan_vid_add net/8021q/vlan_core.c:306 [inline]
>  vlan_vid_add+0x328/0x38c net/8021q/vlan_core.c:336
>  vlan_device_event+0x200/0xc4c net/8021q/vlan.c:385
>  notifier_call_chain kernel/notifier.c:87 [inline]
>  raw_notifier_call_chain+0x7c/0x108 kernel/notifier.c:455
>  __dev_notify_flags+0x170/0x2e8
>  rtnl_newlink_create+0x460/0x6bc net/core/rtnetlink.c:3372
>  __rtnl_newlink net/core/rtnetlink.c:3581 [inline]
>  rtnl_newlink+0x728/0xa04 net/core/rtnetlink.c:3594
>  rtnetlink_rcv_msg+0x484/0x82c net/core/rtnetlink.c:6091
>  netlink_rcv_skb+0xe8/0x1d4 net/netlink/af_netlink.c:2540
>  rtnetlink_rcv+0x28/0x38 net/core/rtnetlink.c:6109
>  netlink_unicast_kernel+0xfc/0x1dc net/netlink/af_netlink.c:1319
>  netlink_unicast+0x164/0x248 net/netlink/af_netlink.c:1345
>  netlink_sendmsg+0x484/0x584 net/netlink/af_netlink.c:1921
>  sock_sendmsg_nosec net/socket.c:714 [inline]
>  sock_sendmsg net/socket.c:734 [inline]
>  ____sys_sendmsg+0x2f8/0x440 net/socket.c:2482
>  ___sys_sendmsg net/socket.c:2536 [inline]
>  __sys_sendmsg+0x1ac/0x228 net/socket.c:2565
>  __do_sys_sendmsg net/socket.c:2574 [inline]
>  __se_sys_sendmsg net/socket.c:2572 [inline]
>  __arm64_sys_sendmsg+0x2c/0x3c net/socket.c:2572
>  __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
>  invoke_syscall arch/arm64/kernel/syscall.c:52 [inline]
>  el0_svc_common+0x138/0x220 arch/arm64/kernel/syscall.c:142
>  do_el0_svc+0x48/0x164 arch/arm64/kernel/syscall.c:206
>  el0_svc+0x58/0x150 arch/arm64/kernel/entry-common.c:637
>  el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
>  el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581
>