syzbot

======================================================
WARNING: possible circular locking dependency detected
5.2.0-next-20190709 #34 Not tainted
------------------------------------------------------
syz-executor186/9066 is trying to acquire lock:
000000007f6e4671 (rtnl_mutex){+.+.}, at: rtnl_lock+0x17/0x20 net/core/rtnetlink.c:72

but task is already holding lock:
000000005575bc3b (&xs->mutex){+.+.}, at: xsk_bind+0x16a/0xe80 net/xdp/xsk.c:436

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&xs->mutex){+.+.}:
       __mutex_lock_common kernel/locking/mutex.c:926 [inline]
       __mutex_lock+0xf7/0x1340 kernel/locking/mutex.c:1073
       mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1088
       xsk_notifier+0x145/0x2a0 net/xdp/xsk.c:764
       notifier_call_chain+0xc2/0x230 kernel/notifier.c:95
       __raw_notifier_call_chain kernel/notifier.c:396 [inline]
       raw_notifier_call_chain+0x2e/0x40 kernel/notifier.c:403
       call_netdevice_notifiers_info+0x3f/0x90 net/core/dev.c:1749
       call_netdevice_notifiers_extack net/core/dev.c:1761 [inline]
       call_netdevice_notifiers net/core/dev.c:1775 [inline]
       rollback_registered_many+0x8d5/0xdf0 net/core/dev.c:8204
       rollback_registered+0x109/0x1d0 net/core/dev.c:8246
       unregister_netdevice_queue net/core/dev.c:9293 [inline]
       unregister_netdevice_queue+0x1ee/0x2c0 net/core/dev.c:9286
       br_dev_delete+0x145/0x1a0 net/bridge/br_if.c:383
       br_del_bridge+0xd7/0x120 net/bridge/br_if.c:483
       br_ioctl_deviceless_stub+0x2b0/0x7c0 net/bridge/br_ioctl.c:376
       sock_ioctl+0x44b/0x790 net/socket.c:1144
       vfs_ioctl fs/ioctl.c:46 [inline]
       file_ioctl fs/ioctl.c:509 [inline]
       do_vfs_ioctl+0xdb6/0x13e0 fs/ioctl.c:696
       ksys_ioctl+0xab/0xd0 fs/ioctl.c:713
       __do_sys_ioctl fs/ioctl.c:720 [inline]
       __se_sys_ioctl fs/ioctl.c:718 [inline]
       __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718
       do_syscall_64+0xfd/0x6a0 arch/x86/entry/common.c:296
       entry_SYSCALL_64_after_hwframe+0x49/0xbe

-> #1 (&net->xdp.lock){+.+.}:
       __mutex_lock_common kernel/locking/mutex.c:926 [inline]
       __mutex_lock+0xf7/0x1340 kernel/locking/mutex.c:1073
       mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1088
       xsk_notifier+0xa3/0x2a0 net/xdp/xsk.c:760
       notifier_call_chain+0xc2/0x230 kernel/notifier.c:95
       __raw_notifier_call_chain kernel/notifier.c:396 [inline]
       raw_notifier_call_chain+0x2e/0x40 kernel/notifier.c:403
       call_netdevice_notifiers_info+0x3f/0x90 net/core/dev.c:1749
       call_netdevice_notifiers_extack net/core/dev.c:1761 [inline]
       call_netdevice_notifiers net/core/dev.c:1775 [inline]
       rollback_registered_many+0x8d5/0xdf0 net/core/dev.c:8204
       rollback_registered+0x109/0x1d0 net/core/dev.c:8246
       unregister_netdevice_queue net/core/dev.c:9293 [inline]
       unregister_netdevice_queue+0x1ee/0x2c0 net/core/dev.c:9286
       br_dev_delete+0x145/0x1a0 net/bridge/br_if.c:383
       br_del_bridge+0xd7/0x120 net/bridge/br_if.c:483
       br_ioctl_deviceless_stub+0x2b0/0x7c0 net/bridge/br_ioctl.c:376
       sock_ioctl+0x44b/0x790 net/socket.c:1144
       vfs_ioctl fs/ioctl.c:46 [inline]
       file_ioctl fs/ioctl.c:509 [inline]
       do_vfs_ioctl+0xdb6/0x13e0 fs/ioctl.c:696
       ksys_ioctl+0xab/0xd0 fs/ioctl.c:713
       __do_sys_ioctl fs/ioctl.c:720 [inline]
       __se_sys_ioctl fs/ioctl.c:718 [inline]
       __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718
       do_syscall_64+0xfd/0x6a0 arch/x86/entry/common.c:296
       entry_SYSCALL_64_after_hwframe+0x49/0xbe

-> #0 (rtnl_mutex){+.+.}:
       check_prev_add kernel/locking/lockdep.c:2405 [inline]
       check_prevs_add kernel/locking/lockdep.c:2507 [inline]
       validate_chain kernel/locking/lockdep.c:2897 [inline]
       __lock_acquire+0x25a9/0x4c30 kernel/locking/lockdep.c:3880
       lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4413
       __mutex_lock_common kernel/locking/mutex.c:926 [inline]
       __mutex_lock+0xf7/0x1340 kernel/locking/mutex.c:1073
       mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1088
       rtnl_lock+0x17/0x20 net/core/rtnetlink.c:72
       xdp_umem_assign_dev+0xbe/0x8f0 net/xdp/xdp_umem.c:96
       xsk_bind+0x4d7/0xe80 net/xdp/xsk.c:502
       __sys_bind+0x239/0x290 net/socket.c:1656
       __do_sys_bind net/socket.c:1667 [inline]
       __se_sys_bind net/socket.c:1665 [inline]
       __x64_sys_bind+0x73/0xb0 net/socket.c:1665
       do_syscall_64+0xfd/0x6a0 arch/x86/entry/common.c:296
       entry_SYSCALL_64_after_hwframe+0x49/0xbe

other info that might help us debug this:

Chain exists of:
  rtnl_mutex --> &net->xdp.lock --> &xs->mutex

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&xs->mutex);
                               lock(&net->xdp.lock);
                               lock(&xs->mutex);
  lock(rtnl_mutex);

 *** DEADLOCK ***

1 lock held by syz-executor186/9066:
 #0: 000000005575bc3b (&xs->mutex){+.+.}, at: xsk_bind+0x16a/0xe80 net/xdp/xsk.c:436

stack backtrace:
CPU: 1 PID: 9066 Comm: syz-executor186 Not tainted 5.2.0-next-20190709 #34
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x172/0x1f0 lib/dump_stack.c:113
 print_circular_bug.cold+0x163/0x172 kernel/locking/lockdep.c:1617
 check_noncircular+0x345/0x3e0 kernel/locking/lockdep.c:1741
 check_prev_add kernel/locking/lockdep.c:2405 [inline]
 check_prevs_add kernel/locking/lockdep.c:2507 [inline]
 validate_chain kernel/locking/lockdep.c:2897 [inline]
 __lock_acquire+0x25a9/0x4c30 kernel/locking/lockdep.c:3880
 lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4413
 __mutex_lock_common kernel/locking/mutex.c:926 [inline]
 __mutex_lock+0xf7/0x1340 kernel/locking/mutex.c:1073
 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1088
 rtnl_lock+0x17/0x20 net/core/rtnetlink.c:72
 xdp_umem_assign_dev+0xbe/0x8f0 net/xdp/xdp_umem.c:96
 xsk_bind+0x4d7/0xe80 net/xdp/xsk.c:502
 __sys_bind+0x239/0x290 net/socket.c:1656
 __do_sys_bind net/socket.c:1667 [inline]
 __se_sys_bind net/socket.c:1665 [inline]
 __x64_sys_bind+0x73/0xb0 net/socket.c:1665
 do_syscall_64+0xfd/0x6a0 arch/x86/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x447909
Code: e8 cc e7 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 3b 08 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fc32958fd98 EFLAGS: 00000246 ORIG_RAX: 0000000000000031
RAX: ffffffffffffffda RBX: 00000000006dcc68 RCX: 0000000000447909
RDX: 0000000000000010 RSI: 0000000020000040 RDI: 0000000000000005
RBP: 00000000006dcc60 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dcc6c
R13: 0000003066736362 R14: 0000000000000000 R15: 0000003066736362