syzbot

FAULT_INJECTION: forcing a failure.
name fail_usercopy, interval 1, probability 0, space 0, times 1
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.3.97/6082 is trying to acquire lock:
ffffffff8d126220 (console_owner){....}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:339 [inline]
ffffffff8d126220 (console_owner){....}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:232 [inline]
ffffffff8d126220 (console_owner){....}-{0:0}, at: console_srcu_read_lock kernel/printk/printk.c:292 [inline]
ffffffff8d126220 (console_owner){....}-{0:0}, at: console_flush_all+0x10a/0xd20 kernel/printk/printk.c:2992

but task is already holding lock:
ffff8880b8f3c018 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:559

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #5 (&rq->__lock){-.-.}-{2:2}:
       _raw_spin_lock_nested+0x32/0x50 kernel/locking/spinlock.c:378
       raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:559
       raw_spin_rq_lock kernel/sched/sched.h:1379 [inline]
       rq_lock kernel/sched/sched.h:1688 [inline]
       task_fork_fair+0x62/0x1f0 kernel/sched/fair.c:12727
       sched_cgroup_fork+0x333/0x3c0 kernel/sched/core.c:4817
       copy_process+0x21fc/0x3d80 kernel/fork.c:2614
       kernel_clone+0x24b/0x8a0 kernel/fork.c:2914
       user_mode_thread+0x111/0x180 kernel/fork.c:2992
       rest_init+0x27/0x300 init/main.c:709
       arch_call_rest_init+0xe/0x10 init/main.c:841
       start_kernel+0x459/0x4e0 init/main.c:1086
       x86_64_start_reservations+0x2a/0x30 arch/x86/kernel/head64.c:555
       copy_bootdata+0x0/0xe0 arch/x86/kernel/head64.c:536
       secondary_startup_64_no_verify+0x179/0x17b

-> #4 (&p->pi_lock){-.-.}-{2:2}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0xb4/0x100 kernel/locking/spinlock.c:162
       class_raw_spinlock_irqsave_constructor include/linux/spinlock.h:522 [inline]
       try_to_wake_up+0x60/0x1190 kernel/sched/core.c:4233
       kick_pool+0x320/0x420 kernel/workqueue.c:1146
       create_worker+0x5e0/0x7d0 kernel/workqueue.c:2218
       workqueue_init+0x306/0x670 kernel/workqueue.c:6736
       kernel_init_freeable+0x3bb/0x580 init/main.c:1550
       kernel_init+0x1d/0x1c0 init/main.c:1455
       ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
       ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293

-> #3 (&pool->lock){-.-.}-{2:2}:
       __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
       _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
       __queue_work+0x69f/0x1020 kernel/workqueue.c:1764
       queue_work_on+0x128/0x1f0 kernel/workqueue.c:1835
       queue_work include/linux/workqueue.h:562 [inline]
       rpm_suspend+0x111e/0x1af0 drivers/base/power/runtime.c:660
       __pm_runtime_idle+0x12f/0x1a0 drivers/base/power/runtime.c:1102
       pm_runtime_put include/linux/pm_runtime.h:454 [inline]
       __device_attach+0x34c/0x420 drivers/base/dd.c:1048
       bus_probe_device+0x180/0x260 drivers/base/bus.c:534
       device_add+0x85b/0xc20 drivers/base/core.c:3683
       serial_base_port_add+0x2f2/0x420 drivers/tty/serial/serial_base_bus.c:178
       serial_core_port_device_add drivers/tty/serial/serial_core.c:3377 [inline]
       serial_core_register_port+0x37d/0x2360 drivers/tty/serial/serial_core.c:3418
       serial8250_register_8250_port+0x15ec/0x1f10 drivers/tty/serial/8250/8250_core.c:1142
       serial_pnp_probe+0x570/0x750 drivers/tty/serial/8250/8250_pnp.c:478
       pnp_device_probe+0x305/0x4b0 drivers/pnp/driver.c:111
       call_driver_probe drivers/base/dd.c:-1 [inline]
       really_probe+0x25b/0xb20 drivers/base/dd.c:658
       __driver_probe_device+0x18c/0x330 drivers/base/dd.c:800
       driver_probe_device+0x4f/0x420 drivers/base/dd.c:830
       __driver_attach+0x44e/0x6e0 drivers/base/dd.c:1216
       bus_for_each_dev+0x235/0x2b0 drivers/base/bus.c:370
       bus_add_driver+0x340/0x630 drivers/base/bus.c:675
       driver_register+0x23a/0x310 drivers/base/driver.c:246
       serial8250_init+0x9a/0x170 drivers/tty/serial/8250/8250_core.c:1243
       do_one_initcall+0x242/0x790 init/main.c:1250
       do_initcall_level+0x137/0x1f0 init/main.c:1312
       do_initcalls+0x69/0xd0 init/main.c:1328
       kernel_init_freeable+0x3ed/0x580 init/main.c:1565
       kernel_init+0x1d/0x1c0 init/main.c:1455
       ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
       ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293

-> #2 (&dev->power.lock){-...}-{2:2}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0xb4/0x100 kernel/locking/spinlock.c:162
       __pm_runtime_resume+0x10f/0x170 drivers/base/power/runtime.c:1169
       pm_runtime_get include/linux/pm_runtime.h:402 [inline]
       __uart_start+0x171/0x3e0 drivers/tty/serial/serial_core.c:148
       uart_write+0x449/0x5d0 drivers/tty/serial/serial_core.c:633
       process_output_block drivers/tty/n_tty.c:580 [inline]
       n_tty_write+0xd34/0x11e0 drivers/tty/n_tty.c:2395
       iterate_tty_write drivers/tty/tty_io.c:1017 [inline]
       file_tty_write+0x54b/0x980 drivers/tty/tty_io.c:1088
       call_write_iter include/linux/fs.h:2018 [inline]
       new_sync_write fs/read_write.c:491 [inline]
       vfs_write+0x46c/0x990 fs/read_write.c:584
       ksys_write+0x150/0x260 fs/read_write.c:637
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #1 (&port_lock_key){-.-.}-{2:2}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0xb4/0x100 kernel/locking/spinlock.c:162
       serial8250_console_write+0x175/0x17f0 drivers/tty/serial/8250/8250_port.c:3433
       console_emit_next_record kernel/printk/printk.c:2944 [inline]
       console_flush_all+0x6db/0xd20 kernel/printk/printk.c:3000
       console_unlock+0xad/0x350 kernel/printk/printk.c:3069
       vprintk_emit+0x497/0x610 kernel/printk/printk.c:2341
       _printk+0xde/0x130 kernel/printk/printk.c:2366
       register_console+0xae2/0xe50 kernel/printk/printk.c:3583
       univ8250_console_init+0x45/0x50 drivers/tty/serial/8250/8250_core.c:717
       console_init+0x17b/0x5d0 kernel/printk/printk.c:3726
       start_kernel+0x2c0/0x4e0 init/main.c:1022
       x86_64_start_reservations+0x2a/0x30 arch/x86/kernel/head64.c:555
       copy_bootdata+0x0/0xe0 arch/x86/kernel/head64.c:536
       secondary_startup_64_no_verify+0x179/0x17b

-> #0 (console_owner){....}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3134 [inline]
       check_prevs_add kernel/locking/lockdep.c:3253 [inline]
       validate_chain kernel/locking/lockdep.c:3869 [inline]
       __lock_acquire+0x2df1/0x7d40 kernel/locking/lockdep.c:5137
       lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5754
       console_lock_spinning_enable kernel/printk/printk.c:1871 [inline]
       console_emit_next_record kernel/printk/printk.c:2938 [inline]
       console_flush_all+0x6a1/0xd20 kernel/printk/printk.c:3000
       console_unlock+0xad/0x350 kernel/printk/printk.c:3069
       vprintk_emit+0x497/0x610 kernel/printk/printk.c:2341
       _printk+0xde/0x130 kernel/printk/printk.c:2366
       fail_dump lib/fault-inject.c:45 [inline]
       should_fail_ex+0x37e/0x4d0 lib/fault-inject.c:153
       strncpy_from_user+0x36/0x2d0 lib/strncpy_from_user.c:118
       strncpy_from_user_nofault+0x71/0x140 mm/maccess.c:186
       bpf_probe_read_user_str_common kernel/trace/bpf_trace.c:212 [inline]
       ____bpf_probe_read_compat_str kernel/trace/bpf_trace.c:307 [inline]
       bpf_probe_read_compat_str+0xe1/0x170 kernel/trace/bpf_trace.c:303
       bpf_prog_88d57d73ead2a882+0x45/0x47
       bpf_dispatcher_nop_func include/linux/bpf.h:1224 [inline]
       __bpf_prog_run include/linux/filter.h:616 [inline]
       bpf_prog_run include/linux/filter.h:623 [inline]
       __bpf_trace_run kernel/trace/bpf_trace.c:2322 [inline]
       bpf_trace_run2+0x1d9/0x3e0 kernel/trace/bpf_trace.c:2361
       __bpf_trace_tlb_flush+0x11e/0x160 include/trace/events/tlb.h:38
       trace_tlb_flush+0xe6/0x110 include/trace/events/tlb.h:38
       switch_mm_irqs_off+0x7bb/0xb40 arch/x86/mm/tlb.c:-1
       context_switch kernel/sched/core.c:5365 [inline]
       __schedule+0xf6f/0x45a0 kernel/sched/core.c:6700
       schedule+0xbd/0x170 kernel/sched/core.c:6774
       schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6833
       __mutex_lock_common kernel/locking/mutex.c:679 [inline]
       __mutex_lock+0x6a9/0xcc0 kernel/locking/mutex.c:747
       rtnl_lock net/core/rtnetlink.c:78 [inline]
       rtnetlink_rcv_msg+0x811/0xfa0 net/core/rtnetlink.c:6469
       netlink_rcv_skb+0x241/0x4d0 net/netlink/af_netlink.c:2545
       netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
       netlink_unicast+0x751/0x8d0 net/netlink/af_netlink.c:1346
       netlink_sendmsg+0x8d0/0xbf0 net/netlink/af_netlink.c:1894
       sock_sendmsg_nosec net/socket.c:730 [inline]
       __sock_sendmsg net/socket.c:745 [inline]
       ____sys_sendmsg+0x5ba/0x960 net/socket.c:2594
       ___sys_sendmsg+0x2a6/0x360 net/socket.c:2648
       __sys_sendmsg net/socket.c:2677 [inline]
       __do_sys_sendmsg net/socket.c:2686 [inline]
       __se_sys_sendmsg+0x1c2/0x2b0 net/socket.c:2684
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

other info that might help us debug this:

Chain exists of:
  console_owner --> &p->pi_lock --> &rq->__lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&rq->__lock);
                               lock(&p->pi_lock);
                               lock(&rq->__lock);
  lock(console_owner);

 *** DEADLOCK ***

5 locks held by syz.3.97/6082:
 #0: ffffffff8e3bfe08 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
 #0: ffffffff8e3bfe08 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x811/0xfa0 net/core/rtnetlink.c:6469
 #1: ffff8880b8f3c018 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:559
 #2: ffffffff8d131fe0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
 #2: ffffffff8d131fe0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline]
 #2: ffffffff8d131fe0 (rcu_read_lock){....}-{1:2}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2321 [inline]
 #2: ffffffff8d131fe0 (rcu_read_lock){....}-{1:2}, at: bpf_trace_run2+0xe6/0x3e0 kernel/trace/bpf_trace.c:2361
 #3: ffffffff8d126300 (console_lock){+.+.}-{0:0}, at: _printk+0xde/0x130 kernel/printk/printk.c:2366
 #4: ffffffff8d00db10 (console_srcu){....}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:339 [inline]
 #4: ffffffff8d00db10 (console_srcu){....}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:232 [inline]
 #4: ffffffff8d00db10 (console_srcu){....}-{0:0}, at: console_srcu_read_lock kernel/printk/printk.c:292 [inline]
 #4: ffffffff8d00db10 (console_srcu){....}-{0:0}, at: console_flush_all+0x10a/0xd20 kernel/printk/printk.c:2992

stack backtrace:
CPU: 1 PID: 6082 Comm: syz.3.97 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106
 check_noncircular+0x2fc/0x400 kernel/locking/lockdep.c:2187
 check_prev_add kernel/locking/lockdep.c:3134 [inline]
 check_prevs_add kernel/locking/lockdep.c:3253 [inline]
 validate_chain kernel/locking/lockdep.c:3869 [inline]
 __lock_acquire+0x2df1/0x7d40 kernel/locking/lockdep.c:5137
 lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5754
 console_lock_spinning_enable kernel/printk/printk.c:1871 [inline]
 console_emit_next_record kernel/printk/printk.c:2938 [inline]
 console_flush_all+0x6a1/0xd20 kernel/printk/printk.c:3000
 console_unlock+0xad/0x350 kernel/printk/printk.c:3069
 vprintk_emit+0x497/0x610 kernel/printk/printk.c:2341
 _printk+0xde/0x130 kernel/printk/printk.c:2366
 fail_dump lib/fault-inject.c:45 [inline]
 should_fail_ex+0x37e/0x4d0 lib/fault-inject.c:153
 strncpy_from_user+0x36/0x2d0 lib/strncpy_from_user.c:118
 strncpy_from_user_nofault+0x71/0x140 mm/maccess.c:186
 bpf_probe_read_user_str_common kernel/trace/bpf_trace.c:212 [inline]
 ____bpf_probe_read_compat_str kernel/trace/bpf_trace.c:307 [inline]
 bpf_probe_read_compat_str+0xe1/0x170 kernel/trace/bpf_trace.c:303
 bpf_prog_88d57d73ead2a882+0x45/0x47
 bpf_dispatcher_nop_func include/linux/bpf.h:1224 [inline]
 __bpf_prog_run include/linux/filter.h:616 [inline]
 bpf_prog_run include/linux/filter.h:623 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2322 [inline]
 bpf_trace_run2+0x1d9/0x3e0 kernel/trace/bpf_trace.c:2361
 __bpf_trace_tlb_flush+0x11e/0x160 include/trace/events/tlb.h:38
 trace_tlb_flush+0xe6/0x110 include/trace/events/tlb.h:38
 switch_mm_irqs_off+0x7bb/0xb40 arch/x86/mm/tlb.c:-1
 context_switch kernel/sched/core.c:5365 [inline]
 __schedule+0xf6f/0x45a0 kernel/sched/core.c:6700
 schedule+0xbd/0x170 kernel/sched/core.c:6774
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6833
 __mutex_lock_common kernel/locking/mutex.c:679 [inline]
 __mutex_lock+0x6a9/0xcc0 kernel/locking/mutex.c:747
 rtnl_lock net/core/rtnetlink.c:78 [inline]
 rtnetlink_rcv_msg+0x811/0xfa0 net/core/rtnetlink.c:6469
 netlink_rcv_skb+0x241/0x4d0 net/netlink/af_netlink.c:2545
 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
 netlink_unicast+0x751/0x8d0 net/netlink/af_netlink.c:1346
 netlink_sendmsg+0x8d0/0xbf0 net/netlink/af_netlink.c:1894
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 ____sys_sendmsg+0x5ba/0x960 net/socket.c:2594
 ___sys_sendmsg+0x2a6/0x360 net/socket.c:2648
 __sys_sendmsg net/socket.c:2677 [inline]
 __do_sys_sendmsg net/socket.c:2686 [inline]
 __se_sys_sendmsg+0x1c2/0x2b0 net/socket.c:2684
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f08d019acb9
Code: Unable to access opcode bytes at 0x7f08d019ac8f.
RSP: 002b:00007ffe9b56dce8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f08d0415fa0 RCX: 00007f08d019acb9
RDX: 000000002000c090 RSI: 0000200000000040 RDI: 0000000000000003
RBP: 00007ffe9b56dd50 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007f08d0415fac R14: 00007f08d0415fa0 R15: 00007f08d0415fa0
 </TASK>
CPU: 1 PID: 6082 Comm: syz.3.97 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106
 fail_dump lib/fault-inject.c:52 [inline]
 should_fail_ex+0x39d/0x4d0 lib/fault-inject.c:153
 strncpy_from_user+0x36/0x2d0 lib/strncpy_from_user.c:118
 strncpy_from_user_nofault+0x71/0x140 mm/maccess.c:186
 bpf_probe_read_user_str_common kernel/trace/bpf_trace.c:212 [inline]
 ____bpf_probe_read_compat_str kernel/trace/bpf_trace.c:307 [inline]
 bpf_probe_read_compat_str+0xe1/0x170 kernel/trace/bpf_trace.c:303
 bpf_prog_88d57d73ead2a882+0x45/0x47
 bpf_dispatcher_nop_func include/linux/bpf.h:1224 [inline]
 __bpf_prog_run include/linux/filter.h:616 [inline]
 bpf_prog_run include/linux/filter.h:623 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2322 [inline]
 bpf_trace_run2+0x1d9/0x3e0 kernel/trace/bpf_trace.c:2361
 __bpf_trace_tlb_flush+0x11e/0x160 include/trace/events/tlb.h:38
 trace_tlb_flush+0xe6/0x110 include/trace/events/tlb.h:38
 switch_mm_irqs_off+0x7bb/0xb40 arch/x86/mm/tlb.c:-1
 context_switch kernel/sched/core.c:5365 [inline]
 __schedule+0xf6f/0x45a0 kernel/sched/core.c:6700
 schedule+0xbd/0x170 kernel/sched/core.c:6774
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6833
 __mutex_lock_common kernel/locking/mutex.c:679 [inline]
 __mutex_lock+0x6a9/0xcc0 kernel/locking/mutex.c:747
 rtnl_lock net/core/rtnetlink.c:78 [inline]
 rtnetlink_rcv_msg+0x811/0xfa0 net/core/rtnetlink.c:6469
 netlink_rcv_skb+0x241/0x4d0 net/netlink/af_netlink.c:2545
 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
 netlink_unicast+0x751/0x8d0 net/netlink/af_netlink.c:1346
 netlink_sendmsg+0x8d0/0xbf0 net/netlink/af_netlink.c:1894
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 ____sys_sendmsg+0x5ba/0x960 net/socket.c:2594
 ___sys_sendmsg+0x2a6/0x360 net/socket.c:2648
 __sys_sendmsg net/socket.c:2677 [inline]
 __do_sys_sendmsg net/socket.c:2686 [inline]
 __se_sys_sendmsg+0x1c2/0x2b0 net/socket.c:2684
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f08d019acb9
Code: Unable to access opcode bytes at 0x7f08d019ac8f.
RSP: 002b:00007ffe9b56dce8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f08d0415fa0 RCX: 00007f08d019acb9
RDX: 000000002000c090 RSI: 0000200000000040 RDI: 0000000000000003
RBP: 00007ffe9b56dd50 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007f08d0415fac R14: 00007f08d0415fa0 R15: 00007f08d0415fa0
 </TASK>