syzbot

INFO: task syz.0.1406:4871 blocked for more than 127 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.1406      state:D stack:0     pid:4871  tgid:4871  ppid:292    flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:6054 [inline]
 __schedule+0x1496/0x20b0 kernel/sched/core.c:7867
 __schedule_loop kernel/sched/core.c:7944 [inline]
 schedule+0xc5/0x240 kernel/sched/core.c:7959
 schedule_preempt_disabled+0x14/0x30 kernel/sched/core.c:8016
 __mutex_lock_common kernel/locking/mutex.c:707 [inline]
 __mutex_lock+0x902/0x1b90 kernel/locking/mutex.c:806
 __mutex_lock_slowpath+0xe/0x20 kernel/locking/mutex.c:1136
 mutex_lock+0x113/0x1d0 kernel/locking/mutex.c:285
 rcu_barrier+0x4d/0x580 kernel/rcu/tree.c:4589
 netdev_run_todo+0x118/0xce0 net/core/dev.c:10912
 rtnl_unlock+0x12/0x20 net/core/rtnetlink.c:152
 tun_detach drivers/net/tun.c:704 [inline]
 tun_chr_close+0xc5/0x150 drivers/net/tun.c:3520
 __fput+0x20b/0xa30 fs/file_table.c:447
 ____fput+0x20/0x30 fs/file_table.c:475
 task_work_run+0x1e8/0x260 kernel/task_work.c:246
 exit_task_work include/linux/task_work.h:43 [inline]
 do_exit+0xa46/0x2850 kernel/exit.c:955
 do_group_exit+0x21f/0x2f0 kernel/exit.c:1098
 __do_sys_exit_group kernel/exit.c:1109 [inline]
 __se_sys_exit_group kernel/exit.c:1107 [inline]
 __x64_sys_exit_group+0x43/0x50 kernel/exit.c:1107
 x64_sys_call+0x2ed2/0x2ee0 arch/x86/include/generated/asm/syscalls_64.h:232
 do_syscall_x64 arch/x86/entry/common.c:47 [inline]
 do_syscall_64+0x57/0xf0 arch/x86/entry/common.c:78
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7f70fbd9de99
RSP: 002b:00007ffe221b0338 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 000000000000000b RCX: 00007f70fbd9de99
RDX: 0000000000000001 RSI: 0000000000000000 RDI: 000000000000000b
RBP: 0000000000001122 R08: 00007ffe221b07c7 R09: 000000000000000b
R10: 00007f70fc025fa0 R11: 0000000000000246 R12: 0000000000000003
R13: 00007f70fc02627c R14: 00007f70fc026278 R15: 00007f70fc026270
 </TASK>
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 37 Comm: khungtaskd Not tainted syzkaller #0 5adf726ab28801c07fd45706e49e1b3a66128c4b
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/25/2026
Call Trace:
 <TASK>
 __dump_stack+0x21/0x30 lib/dump_stack.c:94
 dump_stack_lvl+0x140/0x1c0 lib/dump_stack.c:120
 dump_stack+0x19/0x20 lib/dump_stack.c:129
 nmi_cpu_backtrace+0x2ba/0x2d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x142/0x2c0 lib/nmi_backtrace.c:62
 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:41
 trigger_all_cpu_backtrace include/linux/nmi.h:158 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:267 [inline]
 watchdog+0xe45/0xf90 kernel/hung_task.c:423
 kthread+0x2c7/0x360 kernel/kthread.c:389
 ret_from_fork+0x67/0xa0 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 33 Comm: rcuop/1 Not tainted syzkaller #0 5adf726ab28801c07fd45706e49e1b3a66128c4b
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/25/2026
RIP: 0010:__kasan_check_write+0x5/0x20 mm/kasan/shadow.c:36
Code: 8b 4d 08 31 d2 e8 bb e4 ff ff 5d c3 cc cc cc cc cc 0f 1f 40 00 b8 4a c7 87 1b 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 55 <48> 89 e5 89 f6 48 8b 4d 08 ba 01 00 00 00 e8 88 e4 ff ff 5d c3 cc
RSP: 0018:ffffc90000007750 EFLAGS: 00000246
RAX: 1ffff110207f215a RBX: dffffc0000000000 RCX: ffff88810367df00
RDX: 0000000000000100 RSI: 0000000000000008 RDI: ffff888103f90268
RBP: ffffc900000078d0 R08: ffff88810367df00 R09: 0000000000000002
R10: 000000000000dd86 R11: 0000000000000100 R12: 1ffff92000000efc
R13: 0000000000000000 R14: ffff888103f90000 R15: ffff8881241f9280
FS:  0000000000000000(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055708dc2f1f0 CR3: 0000000169788000 CR4: 00000000003526b0
DR0: 000004000002002c DR1: fffeffffff7fff05 DR2: 0000000080000002
DR3: 0000000000000003 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 nf_hook_bridge_pre net/bridge/br_input.c:301 [inline]
 br_handle_frame+0x5a5/0xba0 net/bridge/br_input.c:424
 __netif_receive_skb_core+0xfc4/0x3a70 net/core/dev.c:5695
 __netif_receive_skb_one_core net/core/dev.c:5799 [inline]
 __netif_receive_skb net/core/dev.c:5914 [inline]
 process_backlog+0x40b/0xaf0 net/core/dev.c:6250
 __napi_poll+0xcd/0x600 net/core/dev.c:6901
 napi_poll net/core/dev.c:6970 [inline]
 net_rx_action+0x5dc/0xd70 net/core/dev.c:7092
 handle_softirqs+0x1aa/0x620 kernel/softirq.c:621
 __do_softirq+0xf/0x16 kernel/softirq.c:659
 do_softirq+0xb8/0x110 kernel/softirq.c:503
 </IRQ>
 <TASK>
 __local_bh_enable_ip+0x74/0x80 kernel/softirq.c:430
 local_bh_enable include/linux/bottom_half.h:33 [inline]
 rcu_do_batch+0x590/0xcb0 kernel/rcu/tree.c:2594
 nocb_cb_wait kernel/rcu/tree_nocb.h:923 [inline]
 rcu_nocb_cb_kthread+0x533/0xb60 kernel/rcu/tree_nocb.h:957
 kthread+0x2c7/0x360 kernel/kthread.c:389
 ret_from_fork+0x67/0xa0 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
net_ratelimit: 101499 callbacks suppressed
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:1e:a3:3f:aa:9a:6c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:1e:a3:3f:aa:9a:6c, vlan:0)
net_ratelimit: 117506 callbacks suppressed
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:1e:a3:3f:aa:9a:6c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:1e:a3:3f:aa:9a:6c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)