Date:   Sat, 29 Dec 2018 02:31:02 -0800
From:   syzbot <syzbot+f621cda8b7e598908efa@...kaller.appspotmail.com>
To:     davem@...emloft.net, linux-hams@...r.kernel.org,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        ralf@...ux-mips.org, syzkaller-bugs@...glegroups.com
Subject: inconsistent lock state in nr_find_socket

Hello,

syzbot found the following crash on:

HEAD commit:    5694cecdb092 Merge tag 'arm64-upstream' of git://git.kerne..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=129ee73f400000
kernel config:  https://syzkaller.appspot.com/x/.config?x=91a256823ef17263
dashboard link: https://syzkaller.appspot.com/bug?extid=f621cda8b7e598908efa
compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=13b2b42d400000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1220489f400000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+f621cda8b7e598908efa@...kaller.appspotmail.com


================================
WARNING: inconsistent lock state
4.20.0+ #389 Not tainted
--------------------------------
inconsistent {IN-SOFTIRQ-W} -> {SOFTIRQ-ON-W} usage.
syz-executor820/11913 [HC0[0]:SC0[0]:HE1:SE1] takes:
000000003a3617a7 (slock-AF_NETROM){+.?.}, at: spin_lock  
include/linux/spinlock.h:329 [inline]
000000003a3617a7 (slock-AF_NETROM){+.?.}, at: nr_find_socket+0x113/0x160  
net/netrom/af_netrom.c:177
{IN-SOFTIRQ-W} state was registered at:
   lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3844
   __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
   _raw_spin_lock+0x2d/0x40 kernel/locking/spinlock.c:144
   spin_lock include/linux/spinlock.h:329 [inline]
   nr_find_listener net/netrom/af_netrom.c:156 [inline]
   nr_rx_frame+0x5f8/0x1db0 net/netrom/af_netrom.c:955
   nr_loopback_timer+0x79/0x160 net/netrom/nr_loopback.c:62
   call_timer_fn+0x272/0x920 kernel/time/timer.c:1325
   expire_timers kernel/time/timer.c:1362 [inline]
   __run_timers+0x7e5/0xc70 kernel/time/timer.c:1681
   run_timer_softirq+0x52/0xb0 kernel/time/timer.c:1694
   __do_softirq+0x30c/0xb2e kernel/softirq.c:292
   invoke_softirq kernel/softirq.c:373 [inline]
   irq_exit+0x17f/0x1c0 kernel/softirq.c:413
   exiting_irq arch/x86/include/asm/apic.h:536 [inline]
   smp_apic_timer_interrupt+0x1cb/0x760 arch/x86/kernel/apic/apic.c:1061
   apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:807
   arch_local_irq_restore arch/x86/include/asm/paravirt.h:761 [inline]
   lock_acquire+0x268/0x520 kernel/locking/lockdep.c:3847
   __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
   _raw_spin_lock+0x2d/0x40 kernel/locking/spinlock.c:144
   spin_lock include/linux/spinlock.h:329 [inline]
   do_anonymous_page mm/memory.c:2947 [inline]
   handle_pte_fault mm/memory.c:3763 [inline]
   __handle_mm_fault+0x298c/0x5670 mm/memory.c:3889
   handle_mm_fault+0x54f/0xc70 mm/memory.c:3926
   do_user_addr_fault arch/x86/mm/fault.c:1423 [inline]
   __do_page_fault+0x5e8/0xe60 arch/x86/mm/fault.c:1489
   do_page_fault+0xf2/0x7e0 arch/x86/mm/fault.c:1520
   page_fault+0x1e/0x30 arch/x86/entry/entry_64.S:1143
irq event stamp: 294
hardirqs last  enabled at (292): [<ffffffff81007da1>]  
trace_hardirqs_on_thunk+0x1a/0x1c
hardirqs last disabled at (293): [<ffffffff8149f9f0>]  
__local_bh_enable_ip+0x120/0x260 kernel/softirq.c:171
softirqs last  enabled at (294): [<ffffffff86fc0d68>] spin_unlock_bh  
include/linux/spinlock.h:374 [inline]
softirqs last  enabled at (294): [<ffffffff86fc0d68>]  
nr_find_socket+0x128/0x160 net/netrom/af_netrom.c:183
softirqs last disabled at (290): [<ffffffff86fc0c64>] spin_lock_bh  
include/linux/spinlock.h:334 [inline]
softirqs last disabled at (290): [<ffffffff86fc0c64>]  
nr_find_socket+0x24/0x160 net/netrom/af_netrom.c:172

other info that might help us debug this:
  Possible unsafe locking scenario:

        CPU0
        ----
   lock(slock-AF_NETROM);
   <Interrupt>
     lock(slock-AF_NETROM);

  *** DEADLOCK ***

1 lock held by syz-executor820/11913:
  #0: 000000003a3617a7 (slock-AF_NETROM){+.?.}, at: spin_lock  
include/linux/spinlock.h:329 [inline]
  #0: 000000003a3617a7 (slock-AF_NETROM){+.?.}, at:  
nr_find_socket+0x113/0x160 net/netrom/af_netrom.c:177

stack backtrace:
CPU: 0 PID: 11913 Comm: syz-executor820 Not tainted 4.20.0+ #389
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+0x1d3/0x2c6 lib/dump_stack.c:113
  print_usage_bug.cold.59+0x320/0x41a kernel/locking/lockdep.c:2472
  valid_state kernel/locking/lockdep.c:2485 [inline]
  mark_lock_irq kernel/locking/lockdep.c:2679 [inline]
  mark_lock+0x1114/0x1cc0 kernel/locking/lockdep.c:3059
  mark_held_locks+0xc7/0x130 kernel/locking/lockdep.c:2737
  __trace_hardirqs_on_caller kernel/locking/lockdep.c:2766 [inline]
  lockdep_hardirqs_on+0x421/0x5c0 kernel/locking/lockdep.c:2811
  trace_hardirqs_on+0xbd/0x310 kernel/trace/trace_preemptirq.c:30
  __local_bh_enable_ip+0x160/0x260 kernel/softirq.c:194
  __raw_spin_unlock_bh include/linux/spinlock_api_smp.h:176 [inline]
  _raw_spin_unlock_bh+0x30/0x40 kernel/locking/spinlock.c:200
  spin_unlock_bh include/linux/spinlock.h:374 [inline]
  nr_find_socket+0x128/0x160 net/netrom/af_netrom.c:183
  nr_find_next_circuit+0x71/0x90 net/netrom/af_netrom.c:225
  nr_connect+0x6cb/0x1350 net/netrom/af_netrom.c:704
  __sys_connect+0x37d/0x4c0 net/socket.c:1664
  __do_sys_connect net/socket.c:1675 [inline]
  __se_sys_connect net/socket.c:1672 [inline]
  __x64_sys_connect+0x73/0xb0 net/socket.c:1672
  do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4482e9
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 0b 01 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f6fed5b1cc8 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: ffffffffffffffda RBX: 00000000006ddc28 RCX: 00000000004482e9
RDX: 0000000000000048 RSI: 0000000020000000 RDI: 0000000000000004
RBP: 00000000006ddc20 R08: 00007ffd44256f4f R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006ddc2c
R13: 00007ffd44256f4f R14: 00007f6fed5b29c0 R15: 00000000006ddc20


---
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