Message-ID: <00000000000037c7d5056f84cabc@google.com>
Date:   Mon, 25 Jun 2018 22:30:02 -0700
From:   syzbot <syzbot+71aeaaf993d216185076@...kaller.appspotmail.com>
To:     ast@...nel.org, daniel@...earbox.net, linux-kernel@...r.kernel.org,
        netdev@...r.kernel.org, syzkaller-bugs@...glegroups.com
Subject: WARNING: ODEBUG bug in sock_hash_free

Hello,

syzbot found the following crash on:

HEAD commit:    f0dc7f9c6dd9 Merge git://git.kernel.org/pub/scm/linux/kern..
git tree:       bpf-next
console output: https://syzkaller.appspot.com/x/log.txt?x=1725589f800000
kernel config:  https://syzkaller.appspot.com/x/.config?x=fa9c20c48788d1c1
dashboard link: https://syzkaller.appspot.com/bug?extid=71aeaaf993d216185076
compiler:       gcc (GCC) 8.0.1 20180413 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+71aeaaf993d216185076@...kaller.appspotmail.com

------------[ cut here ]------------
ODEBUG: free active (active state 1) object type: rcu_head hint:            
(null)
WARNING: CPU: 1 PID: 4959 at lib/debugobjects.c:329  
debug_print_object+0x16a/0x210 lib/debugobjects.c:326
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 4959 Comm: kworker/1:3 Not tainted 4.17.0+ #39
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Workqueue: events bpf_map_free_deferred
Call Trace:
  __dump_stack lib/dump_stack.c:77 [inline]
  dump_stack+0x1b9/0x294 lib/dump_stack.c:113
  panic+0x22f/0x4de kernel/panic.c:184
  __warn.cold.8+0x163/0x1b3 kernel/panic.c:536
  report_bug+0x252/0x2d0 lib/bug.c:186
  fixup_bug arch/x86/kernel/traps.c:178 [inline]
  do_error_trap+0x1fc/0x4d0 arch/x86/kernel/traps.c:296
  do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:316
  invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:992
RIP: 0010:debug_print_object+0x16a/0x210 lib/debugobjects.c:326
Code: 1a 88 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 92 00 00 00 48 8b 14 dd  
60 75 1a 88 4c 89 f6 48 c7 c7 e0 6a 1a 88 e8 06 62 ec fd <0f> 0b 83 05 39  
5b 44 06 01 48 83 c4 18 5b 41 5c 41 5d 41 5e 41 5f
RSP: 0018:ffff880198e47490 EFLAGS: 00010082
RAX: 0000000000000051 RBX: 0000000000000003 RCX: ffffffff81854ed8
RDX: 0000000000000000 RSI: ffffffff8161f371 RDI: 0000000000000001
RBP: ffff880198e474d0 R08: ffff8801d84b2240 R09: ffffed003b5e3ec2
R10: ffffed003b5e3ec2 R11: ffff8801daf1f617 R12: 0000000000000001
R13: ffffffff88f91d80 R14: ffffffff881a6f80 R15: 0000000000000000
  __debug_check_no_obj_freed lib/debugobjects.c:783 [inline]
  debug_check_no_obj_freed+0x3a6/0x584 lib/debugobjects.c:815
  kfree+0xc7/0x260 mm/slab.c:3812
  sock_hash_free+0x24e/0x6e0 kernel/bpf/sockmap.c:2093
  bpf_map_free_deferred+0xba/0xf0 kernel/bpf/syscall.c:262
  process_one_work+0xc64/0x1b70 kernel/workqueue.c:2153
  worker_thread+0x181/0x13a0 kernel/workqueue.c:2296
  kthread+0x345/0x410 kernel/kthread.c:240
  ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412

======================================================
WARNING: possible circular locking dependency detected
4.17.0+ #39 Not tainted
------------------------------------------------------
kworker/1:3/4959 is trying to acquire lock:
00000000190110fa ((console_sem).lock){-...}, at: down_trylock+0x13/0x70  
kernel/locking/semaphore.c:136

but task is already holding lock:
00000000af3150e8 (&obj_hash[i].lock){-.-.}, at: __debug_check_no_obj_freed  
lib/debugobjects.c:774 [inline]
00000000af3150e8 (&obj_hash[i].lock){-.-.}, at:  
debug_check_no_obj_freed+0x159/0x584 lib/debugobjects.c:815

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&obj_hash[i].lock){-.-.}:
        __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
        _raw_spin_lock_irqsave+0x96/0xc0 kernel/locking/spinlock.c:152
        __debug_object_init+0x11f/0x12c0 lib/debugobjects.c:381
        debug_object_init+0x16/0x20 lib/debugobjects.c:429
        debug_hrtimer_init kernel/time/hrtimer.c:410 [inline]
        debug_init kernel/time/hrtimer.c:458 [inline]
        hrtimer_init+0x8f/0x460 kernel/time/hrtimer.c:1308
        init_dl_task_timer+0x1b/0x50 kernel/sched/deadline.c:1056
        __sched_fork+0x2a8/0x570 kernel/sched/core.c:2184
        init_idle+0x75/0x7a0 kernel/sched/core.c:5404
        sched_init+0xbeb/0xd10 kernel/sched/core.c:6102
        start_kernel+0x475/0x92d init/main.c:602
        x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:452
        x86_64_start_kernel+0x76/0x79 arch/x86/kernel/head64.c:433
        secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:242

-> #2 (&rq->lock){-.-.}:
        __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
        _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:144
        rq_lock kernel/sched/sched.h:1805 [inline]
        task_fork_fair+0x8a/0x660 kernel/sched/fair.c:9953
        sched_fork+0x43e/0xb30 kernel/sched/core.c:2380
        copy_process.part.38+0x1bf1/0x7180 kernel/fork.c:1765
        copy_process kernel/fork.c:1608 [inline]
        _do_fork+0x291/0x12a0 kernel/fork.c:2091
        kernel_thread+0x34/0x40 kernel/fork.c:2150
        rest_init+0x22/0xe4 init/main.c:408
        start_kernel+0x906/0x92d init/main.c:738
        x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:452
        x86_64_start_kernel+0x76/0x79 arch/x86/kernel/head64.c:433
        secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:242

-> #1 (&p->pi_lock){-.-.}:
        __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
        _raw_spin_lock_irqsave+0x96/0xc0 kernel/locking/spinlock.c:152
        try_to_wake_up+0xca/0x1280 kernel/sched/core.c:1984
        wake_up_process+0x10/0x20 kernel/sched/core.c:2147
        __up.isra.1+0x1b8/0x290 kernel/locking/semaphore.c:262
        up+0x12f/0x1b0 kernel/locking/semaphore.c:187
        __up_console_sem+0xbe/0x1b0 kernel/printk/printk.c:242
        console_unlock+0x79a/0x10a0 kernel/printk/printk.c:2411
        vprintk_emit+0x6b2/0xde0 kernel/printk/printk.c:1907
        vprintk_default+0x28/0x30 kernel/printk/printk.c:1948
        vprintk_func+0x7a/0xe7 kernel/printk/printk_safe.c:382
        printk+0x9e/0xba kernel/printk/printk.c:1981
        load_umh+0x51/0xbd net/bpfilter/bpfilter_kern.c:99
        do_one_initcall+0x127/0x913 init/main.c:884
        do_initcall_level init/main.c:952 [inline]
        do_initcalls init/main.c:960 [inline]
        do_basic_setup init/main.c:978 [inline]
        kernel_init_freeable+0x49b/0x58e init/main.c:1135
        kernel_init+0x11/0x1b3 init/main.c:1061
        ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412

-> #0 ((console_sem).lock){-...}:
        lock_acquire+0x1dc/0x520 kernel/locking/lockdep.c:3924
        __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
        _raw_spin_lock_irqsave+0x96/0xc0 kernel/locking/spinlock.c:152
        down_trylock+0x13/0x70 kernel/locking/semaphore.c:136
        __down_trylock_console_sem+0xae/0x200 kernel/printk/printk.c:225
        console_trylock+0x15/0xa0 kernel/printk/printk.c:2230
        console_trylock_spinning kernel/printk/printk.c:1643 [inline]
        vprintk_emit+0x699/0xde0 kernel/printk/printk.c:1906
        vprintk_default+0x28/0x30 kernel/printk/printk.c:1948
        vprintk_func+0x7a/0xe7 kernel/printk/printk_safe.c:382
        printk+0x9e/0xba kernel/printk/printk.c:1981
        __warn_printk+0x83/0xd0 kernel/panic.c:590
        debug_print_object+0x16a/0x210 lib/debugobjects.c:326
        __debug_check_no_obj_freed lib/debugobjects.c:783 [inline]
        debug_check_no_obj_freed+0x3a6/0x584 lib/debugobjects.c:815
        kfree+0xc7/0x260 mm/slab.c:3812
        sock_hash_free+0x24e/0x6e0 kernel/bpf/sockmap.c:2093
        bpf_map_free_deferred+0xba/0xf0 kernel/bpf/syscall.c:262
        process_one_work+0xc64/0x1b70 kernel/workqueue.c:2153
        worker_thread+0x181/0x13a0 kernel/workqueue.c:2296
        kthread+0x345/0x410 kernel/kthread.c:240
        ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412

other info that might help us debug this:

Chain exists of:
   (console_sem).lock --> &rq->lock --> &obj_hash[i].lock

  Possible unsafe locking scenario:

        CPU0                    CPU1
        ----                    ----
   lock(&obj_hash[i].lock);
                                lock(&rq->lock);
                                lock(&obj_hash[i].lock);
   lock((console_sem).lock);

  *** DEADLOCK ***

4 locks held by kworker/1:3/4959:
  #0: 00000000f67deee4 ((wq_completion)"events"){+.+.}, at:  
__write_once_size include/linux/compiler.h:215 [inline]
  #0: 00000000f67deee4 ((wq_completion)"events"){+.+.}, at:  
arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
  #0: 00000000f67deee4 ((wq_completion)"events"){+.+.}, at: atomic64_set  
include/asm-generic/atomic-instrumented.h:40 [inline]
  #0: 00000000f67deee4 ((wq_completion)"events"){+.+.}, at: atomic_long_set  
include/asm-generic/atomic-long.h:59 [inline]
  #0: 00000000f67deee4 ((wq_completion)"events"){+.+.}, at: set_work_data  
kernel/workqueue.c:617 [inline]
  #0: 00000000f67deee4 ((wq_completion)"events"){+.+.}, at:  
set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
  #0: 00000000f67deee4 ((wq_completion)"events"){+.+.}, at:  
process_one_work+0xb35/0x1b70 kernel/workqueue.c:2124
  #1: 00000000776b40d0 ((work_completion)(&map->work)){+.+.}, at:  
process_one_work+0xb8c/0x1b70 kernel/workqueue.c:2128
  #2: 000000002a359661 (rcu_read_lock){....}, at: sock_hash_free+0x0/0x6e0  
include/net/sock.h:2176
  #3: 00000000af3150e8 (&obj_hash[i].lock){-.-.}, at:  
__debug_check_no_obj_freed lib/debugobjects.c:774 [inline]
  #3: 00000000af3150e8 (&obj_hash[i].lock){-.-.}, at:  
debug_check_no_obj_freed+0x159/0x584 lib/debugobjects.c:815

stack backtrace:
CPU: 1 PID: 4959 Comm: kworker/1:3 Not tainted 4.17.0+ #39
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Workqueue: events bpf_map_free_deferred
Call Trace:
  __dump_stack lib/dump_stack.c:77 [inline]
  dump_stack+0x1b9/0x294 lib/dump_stack.c:113
  print_circular_bug.isra.36.cold.56+0x1bd/0x27d  
kernel/locking/lockdep.c:1227
  check_prev_add kernel/locking/lockdep.c:1867 [inline]
  check_prevs_add kernel/locking/lockdep.c:1980 [inline]
  validate_chain kernel/locking/lockdep.c:2421 [inline]
  __lock_acquire+0x343e/0x5140 kernel/locking/lockdep.c:3435
  lock_acquire+0x1dc/0x520 kernel/locking/lockdep.c:3924
  __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
  _raw_spin_lock_irqsave+0x96/0xc0 kernel/locking/spinlock.c:152
  down_trylock+0x13/0x70 kernel/locking/semaphore.c:136
  __down_trylock_console_sem+0xae/0x200 kernel/printk/printk.c:225
  console_trylock+0x15/0xa0 kernel/printk/printk.c:2230
  console_trylock_spinning kernel/printk/printk.c:1643 [inline]
  vprintk_emit+0x699/0xde0 kernel/printk/printk.c:1906
  vprintk_default+0x28/0x30 kernel/printk/printk.c:1948
  vprintk_func+0x7a/0xe7 kernel/printk/printk_safe.c:382
  printk+0x9e/0xba kernel/printk/printk.c:1981
  __warn_printk+0x83/0xd0 kernel/panic.c:590
  debug_print_object+0x16a/0x210 lib/debugobjects.c:326
  __debug_check_no_obj_freed lib/debugobjects.c:783 [inline]
  debug_check_no_obj_freed+0x3a6/0x584 lib/debugobjects.c:815
  kfree+0xc7/0x260 mm/slab.c:3812
  sock_hash_free+0x24e/0x6e0 kernel/bpf/sockmap.c:2093
  bpf_map_free_deferred+0xba/0xf0 kernel/bpf/syscall.c:262
  process_one_work+0xc64/0x1b70 kernel/workqueue.c:2153
  worker_thread+0x181/0x13a0 kernel/workqueue.c:2296
  kthread+0x345/0x410 kernel/kthread.c:240
  ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412
Shutting down cpus with NMI
Dumping ftrace buffer:
    (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..


---
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