INFO: task hung in tun_chr_close (4)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 3f8a27f9e27b Linux 4.19.211
git tree: linux-4.19.y
console output: https://syzkaller.appspot.com/x/log.txt?x=17e83791480000
kernel config: https://syzkaller.appspot.com/x/.config?x=9b9277b418617afe
dashboard link: https://syzkaller.appspot.com/bug?extid=4d107adbee80326ca85c
compiler: gcc version 10.2.1 20210110 (Debian 10.2.1-6)

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/98c0bdb4abb3/disk-3f8a27f9.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ea228ff02669/vmlinux-3f8a27f9.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+4d107a...@syzkaller.appspotmail.com

Bluetooth: hci7: command 0x040f tx timeout
Bluetooth: hci7: command 0x0419 tx timeout
Bluetooth: hci2: command tx timeout
Bluetooth: hci2: command 0x1001 tx timeout
Bluetooth: hci2: unexpected event for opcode 0x1001
INFO: task syz-executor.2:8186 blocked for more than 140 seconds.
Not tainted 4.19.211-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.2 D24216 8186 1 0x80000006
Call Trace:
context_switch kernel/sched/core.c:2828 [inline]
__schedule+0x887/0x2040 kernel/sched/core.c:3517
schedule+0x8d/0x1b0 kernel/sched/core.c:3561
schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:3619
__mutex_lock_common kernel/locking/mutex.c:1016 [inline]
__mutex_lock+0x5f0/0x1190 kernel/locking/mutex.c:1078
tun_detach drivers/net/tun.c:759 [inline]
tun_chr_close+0x3a/0x180 drivers/net/tun.c:3323
__fput+0x2ce/0x890 fs/file_table.c:278
task_work_run+0x148/0x1c0 kernel/task_work.c:113
exit_task_work include/linux/task_work.h:22 [inline]
do_exit+0xbf3/0x2be0 kernel/exit.c:870
do_group_exit+0x125/0x310 kernel/exit.c:967
get_signal+0x3f2/0x1f70 kernel/signal.c:2589
do_signal+0x8f/0x1670 arch/x86/kernel/signal.c:799
Bluetooth: hci4: command 0x0406 tx timeout
exit_to_usermode_loop+0x204/0x2a0 arch/x86/entry/common.c:163
prepare_exit_to_usermode arch/x86/entry/common.c:198 [inline]
syscall_return_slowpath arch/x86/entry/common.c:271 [inline]
do_syscall_64+0x538/0x620 arch/x86/entry/common.c:296
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7fba9c5fcdfb
Code: Bad RIP value.
RSP: 002b:00007ffe573a59b0 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: fffffffffffffff4 RBX: 0000000000000000 RCX: 00007fba9c5fcdfb
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011
RBP: 0000000000000001 R08: 0000000000000000 R09: 0000555557047400
R10: 00005555570476d0 R11: 0000000000000246 R12: 0000000000000001
R13: 0000000000000000 R14: 0000000000000001 R15: 00007ffe573a5a90
INFO: task kworker/0:0:27730 blocked for more than 140 seconds.
Not tainted 4.19.211-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kworker/0:0 D27264 27730 2 0x80000000
Workqueue: events linkwatch_event
Call Trace:
context_switch kernel/sched/core.c:2828 [inline]
__schedule+0x887/0x2040 kernel/sched/core.c:3517
schedule+0x8d/0x1b0 kernel/sched/core.c:3561
schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:3619
__mutex_lock_common kernel/locking/mutex.c:1016 [inline]
__mutex_lock+0x5f0/0x1190 kernel/locking/mutex.c:1078
linkwatch_event+0xb/0x60 net/core/link_watch.c:236
process_one_work+0x864/0x1570 kernel/workqueue.c:2153
worker_thread+0x64c/0x1130 kernel/workqueue.c:2296
kthread+0x33f/0x460 kernel/kthread.c:259
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
INFO: task kworker/1:4:6249 blocked for more than 140 seconds.
Not tainted 4.19.211-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kworker/1:4 D27248 6249 2 0x80000000
Workqueue: ipv6_addrconf addrconf_dad_work
Call Trace:
context_switch kernel/sched/core.c:2828 [inline]
__schedule+0x887/0x2040 kernel/sched/core.c:3517
schedule+0x8d/0x1b0 kernel/sched/core.c:3561
schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:3619
__mutex_lock_common kernel/locking/mutex.c:1016 [inline]
__mutex_lock+0x5f0/0x1190 kernel/locking/mutex.c:1078
addrconf_dad_work+0x9c/0x10a0 net/ipv6/addrconf.c:3989
process_one_work+0x864/0x1570 kernel/workqueue.c:2153
worker_thread+0x64c/0x1130 kernel/workqueue.c:2296
kthread+0x33f/0x460 kernel/kthread.c:259
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
INFO: task syz-executor.4:23748 blocked for more than 140 seconds.
Not tainted 4.19.211-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.4 D24368 23748 1 0x00000004
Call Trace:
context_switch kernel/sched/core.c:2828 [inline]
__schedule+0x887/0x2040 kernel/sched/core.c:3517
schedule+0x8d/0x1b0 kernel/sched/core.c:3561
schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:3619
__mutex_lock_common kernel/locking/mutex.c:1016 [inline]
__mutex_lock+0x5f0/0x1190 kernel/locking/mutex.c:1078
rtnl_lock net/core/rtnetlink.c:77 [inline]
rtnetlink_rcv_msg+0x3fe/0xb80 net/core/rtnetlink.c:4779
netlink_rcv_skb+0x160/0x440 net/netlink/af_netlink.c:2463
netlink_unicast_kernel net/netlink/af_netlink.c:1325 [inline]
netlink_unicast+0x4d5/0x690 net/netlink/af_netlink.c:1351
netlink_sendmsg+0x6c3/0xc50 net/netlink/af_netlink.c:1917
sock_sendmsg_nosec net/socket.c:651 [inline]
sock_sendmsg+0xc3/0x120 net/socket.c:661
__sys_sendto+0x21a/0x320 net/socket.c:1899
__do_sys_sendto net/socket.c:1911 [inline]
__se_sys_sendto net/socket.c:1907 [inline]
__x64_sys_sendto+0xdd/0x1b0 net/socket.c:1907
do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7ff5786630fc
Code: Bad RIP value.
RSP: 002b:00007fffb69441d0 EFLAGS: 00000293 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007ff5792f9620 RCX: 00007ff5786630fc
RDX: 0000000000000040 RSI: 00007ff5792f9670 RDI: 0000000000000003
RBP: 0000000000000000 R08: 00007fffb6944224 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000000
R13: 00007ff5792f9670 R14: 0000000000000003 R15: 0000000000000000

Showing all locks held in the system:
1 lock held by systemd/1:
1 lock held by khungtaskd/1570:
#0: 00000000ba20d33b (rcu_read_lock){....}, at: debug_show_all_locks+0x53/0x265 kernel/locking/lockdep.c:4441
1 lock held by systemd-journal/4690:
3 locks held by syz-fuzzer/8146:
2 locks held by syz-fuzzer/10086:
1 lock held by syz-executor.2/8186:
#0: 00000000ade72864 (rtnl_mutex){+.+.}, at: tun_detach drivers/net/tun.c:759 [inline]
#0: 00000000ade72864 (rtnl_mutex){+.+.}, at: tun_chr_close+0x3a/0x180 drivers/net/tun.c:3323
3 locks held by kworker/u4:5/8842:
3 locks held by kworker/0:0/27730:
#0: 00000000212231a9 ((wq_completion)"events"){+.+.}, at: process_one_work+0x767/0x1570 kernel/workqueue.c:2124
#1: 000000009464bacc ((linkwatch_work).work){+.+.}, at: process_one_work+0x79c/0x1570 kernel/workqueue.c:2128
#2: 00000000ade72864 (rtnl_mutex){+.+.}, at: linkwatch_event+0xb/0x60 net/core/link_watch.c:236
3 locks held by kworker/1:4/6249:
#0: 0000000087f638da ((wq_completion)"%s"("ipv6_addrconf")){+.+.}, at: process_one_work+0x767/0x1570 kernel/workqueue.c:2124
#1: 00000000453260bd ((work_completion)(&(&ifa->dad_work)->work)){+.+.}, at: process_one_work+0x79c/0x1570 kernel/workqueue.c:2128
#2: 00000000ade72864 (rtnl_mutex){+.+.}, at: addrconf_dad_work+0x9c/0x10a0 net/ipv6/addrconf.c:3989
3 locks held by kworker/u4:9/11101:
3 locks held by kworker/u4:10/20471:
2 locks held by syz-executor.4/23489:
#0: 00000000ade72864 (rtnl_mutex){+.+.}, at: tun_detach drivers/net/tun.c:759 [inline]
#0: 00000000ade72864 (rtnl_mutex){+.+.}, at: tun_chr_close+0x3a/0x180 drivers/net/tun.c:3323
#1: 000000000126aa6c (rcu_preempt_state.exp_mutex){+.+.}, at: exp_funnel_lock kernel/rcu/tree_exp.h:297 [inline]
#1: 000000000126aa6c (rcu_preempt_state.exp_mutex){+.+.}, at: _synchronize_rcu_expedited+0x4dc/0x6f0 kernel/rcu/tree_exp.h:667
2 locks held by syz-executor.0/23577:
1 lock held by syz-executor.4/23748:
#0: 00000000ade72864 (rtnl_mutex){+.+.}, at: rtnl_lock net/core/rtnetlink.c:77 [inline]
#0: 00000000ade72864 (rtnl_mutex){+.+.}, at: rtnetlink_rcv_msg+0x3fe/0xb80 net/core/rtnetlink.c:4779
3 locks held by kworker/0:3/23955:
1 lock held by syz-executor.4/23980:
#0: 00000000ade72864 (rtnl_mutex){+.+.}, at: rtnl_lock net/core/rtnetlink.c:77 [inline]
#0: 00000000ade72864 (rtnl_mutex){+.+.}, at: rtnetlink_rcv_msg+0x3fe/0xb80 net/core/rtnetlink.c:4779
1 lock held by syz-executor.0/23994:
#0: 00000000ade72864 (rtnl_mutex){+.+.}, at: rtnl_lock net/core/rtnetlink.c:77 [inline]
#0: 00000000ade72864 (rtnl_mutex){+.+.}, at: rtnetlink_rcv_msg+0x3fe/0xb80 net/core/rtnetlink.c:4779

=============================================

NMI backtrace for cpu 1
CPU: 1 PID: 1570 Comm: khungtaskd Not tainted 4.19.211-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/12/2023
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x1fc/0x2ef lib/dump_stack.c:118
nmi_cpu_backtrace.cold+0x63/0xa2 lib/nmi_backtrace.c:101
nmi_trigger_cpumask_backtrace+0x1a6/0x1f0 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:203 [inline]
watchdog+0x991/0xe60 kernel/hung_task.c:287
kthread+0x33f/0x460 kernel/kthread.c:259
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 23955 Comm: kworker/0:3 Not tainted 4.19.211-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/12/2023
Workqueue: events iterate_cleanup_work
RIP: 0010:__orc_find+0x8b/0xf0 arch/x86/kernel/unwind_orc.c:52
Code: 85 00 48 89 d8 48 c1 e8 03 42 0f b6 14 38 48 89 d8 83 e0 07 83 c0 03 38 d0 7c 04 84 d2 75 48 48 63 03 48 01 d8 48 39 c1 73 b0 <4c> 8d 63 fc 49 39 ec 73 b3 4d 29 ee 49 c1 fe 02 4b 8d 04 76 48 8d
RSP: 0018:ffff8880ba007748 EFLAGS: 00000087
RAX: ffffffff87351899 RBX: ffffffff8b7e5d98 RCX: ffffffff8735188e
RDX: 0000000000000000 RSI: ffffffff8c01e8ca RDI: ffffffff8b7e5d90
RBP: ffffffff8b7e5d90 R08: 0000000000000000 R09: ffffffff8c01e8ca
R10: ffff8880ba00791f R11: 0000000000074071 R12: ffffffff8b7e5da0
R13: ffffffff8b7e5d90 R14: ffffffff8b7e5d90 R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff8880ba000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000562d00205018 CR3: 0000000096b11000 CR4: 00000000003406f0
DR0: 0000000000000000 DR1: 0080ffff00000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Call Trace:
<IRQ>
orc_find arch/x86/kernel/unwind_orc.c:159 [inline]
unwind_next_frame+0x339/0x1400 arch/x86/kernel/unwind_orc.c:422
__save_stack_trace+0x9f/0x190 arch/x86/kernel/stacktrace.c:44
save_stack mm/kasan/kasan.c:448 [inline]
set_track mm/kasan/kasan.c:460 [inline]
__kasan_slab_free+0x126/0x1f0 mm/kasan/kasan.c:521
__cache_free mm/slab.c:3503 [inline]
kfree+0xcc/0x210 mm/slab.c:3822
skb_free_head net/core/skbuff.c:563 [inline]
skb_release_data+0x6de/0x920 net/core/skbuff.c:583
skb_release_all net/core/skbuff.c:640 [inline]
__kfree_skb net/core/skbuff.c:654 [inline]
consume_skb+0x113/0x3d0 net/core/skbuff.c:714
can_receive+0x358/0x530 net/can/af_can.c:712
canfd_rcv+0x12f/0x1d0 net/can/af_can.c:764
__netif_receive_skb_one_core+0x114/0x180 net/core/dev.c:4954
__netif_receive_skb+0x27/0x1c0 net/core/dev.c:5066
process_backlog+0x241/0x700 net/core/dev.c:5849
napi_poll net/core/dev.c:6280 [inline]
net_rx_action+0x4ac/0xfb0 net/core/dev.c:6346
__do_softirq+0x265/0x980 kernel/softirq.c:292
invoke_softirq kernel/softirq.c:372 [inline]
irq_exit+0x215/0x260 kernel/softirq.c:412
exiting_irq arch/x86/include/asm/apic.h:536 [inline]
smp_apic_timer_interrupt+0x136/0x550 arch/x86/kernel/apic/apic.c:1098
apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:894
</IRQ>
RIP: 0010:should_resched arch/x86/include/asm/preempt.h:99 [inline]
RIP: 0010:__local_bh_enable_ip+0x18d/0x270 kernel/softirq.c:196
Code: 00 00 00 00 fc ff df 48 c1 e8 03 80 3c 10 00 0f 85 dd 00 00 00 48 83 3d c8 5f b8 08 00 0f 84 8d 00 00 00 fb 66 0f 1f 44 00 00 <65> 8b 05 6c bc c8 7e 85 c0 74 7d 5b 5d 41 5c c3 80 3d f3 87 d5 09
RSP: 0018:ffff88809c4a7bd0 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff13
RAX: 1ffffffff13e3053 RBX: 0000000000000200 RCX: 1ffff11012a65da2
RDX: dffffc0000000000 RSI: ffff88809532ecf0 RDI: ffff88809532ecc4
RBP: ffffffff86a43e12 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff88809532e440
R13: 000000000000bb63 R14: 0000000000000000 R15: 0000000000000001
local_bh_enable include/linux/bottom_half.h:32 [inline]
get_next_corpse net/netfilter/nf_conntrack_core.c:1907 [inline]
nf_ct_iterate_cleanup+0x239/0x520 net/netfilter/nf_conntrack_core.c:1930
nf_ct_iterate_cleanup_net net/netfilter/nf_conntrack_core.c:2015 [inline]
nf_ct_iterate_cleanup_net+0x113/0x170 net/netfilter/nf_conntrack_core.c:2000
iterate_cleanup_work+0x43/0xd0 net/ipv6/netfilter/nf_nat_masquerade_ipv6.c:113
process_one_work+0x864/0x1570 kernel/workqueue.c:2153
worker_thread+0x64c/0x1130 kernel/workqueue.c:2296
kthread+0x33f/0x460 kernel/kthread.c:259
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415


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