Re: [syzbot] [cgroups?] possible deadlock in console_lock_spinning_enable (5)

From: syzbot
Date: Wed Jan 22 2025 - 05:54:12 EST

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In reply to: Hillf Danton: "Re: [syzbot] [cgroups?] possible deadlock in console_lock_spinning_enable (5)"
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Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
possible deadlock in console_lock_spinning_enable

FAULT_INJECTION: forcing a failure.
name fail_usercopy, interval 1, probability 0, space 0, times 1
======================================================
WARNING: possible circular locking dependency detected
6.13.0-syzkaller-gc4b9570cfb63-dirty #0 Not tainted
------------------------------------------------------
syz.1.427/7673 is trying to acquire lock:
ffffffff8e0cb740 (console_owner){-...}-{0:0}, at: console_lock_spinning_enable+0x9f/0xd0 kernel/printk/printk.c:1924

but task is already holding lock:
ffff8880b863ec18 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x29/0x130 kernel/sched/core.c:598

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #4 (&rq->__lock){-.-.}-{2:2}:
_raw_spin_lock_nested+0x31/0x40 kernel/locking/spinlock.c:378
raw_spin_rq_lock_nested+0x29/0x130 kernel/sched/core.c:598
raw_spin_rq_lock kernel/sched/sched.h:1519 [inline]
task_rq_lock+0xcf/0x3b0 kernel/sched/core.c:700
cgroup_move_task+0x82/0x250 kernel/sched/psi.c:1161
css_set_move_task+0x288/0x5f0 kernel/cgroup/cgroup.c:898
cgroup_post_fork+0x1c6/0x910 kernel/cgroup/cgroup.c:6691
copy_process+0x5034/0x8d10 kernel/fork.c:2617
kernel_clone+0xfd/0x960 kernel/fork.c:2803
user_mode_thread+0xb4/0xf0 kernel/fork.c:2881
rest_init+0x23/0x2b0 init/main.c:712
start_kernel+0x3e9/0x4d0 init/main.c:1103
x86_64_start_reservations+0x18/0x30 arch/x86/kernel/head64.c:507
x86_64_start_kernel+0xb2/0xc0 arch/x86/kernel/head64.c:488
common_startup_64+0x13e/0x148

-> #3 (&p->pi_lock){-.-.}-{2:2}:
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x3a/0x60 kernel/locking/spinlock.c:162
class_raw_spinlock_irqsave_constructor include/linux/spinlock.h:551 [inline]
try_to_wake_up+0xb6/0x1490 kernel/sched/core.c:4209
__wake_up_common+0x131/0x1e0 kernel/sched/wait.c:89
__wake_up_common_lock kernel/sched/wait.c:106 [inline]
__wake_up+0x31/0x60 kernel/sched/wait.c:127
tty_port_default_wakeup+0x2a/0x40 drivers/tty/tty_port.c:69
serial8250_tx_chars+0x68e/0x860 drivers/tty/serial/8250/8250_port.c:1841
serial8250_handle_irq+0x74d/0xc80 drivers/tty/serial/8250/8250_port.c:1949
serial8250_default_handle_irq+0x9a/0x210 drivers/tty/serial/8250/8250_port.c:1969
serial8250_interrupt+0x103/0x210 drivers/tty/serial/8250/8250_core.c:86
__handle_irq_event_percpu+0x229/0x7d0 kernel/irq/handle.c:158
handle_irq_event_percpu kernel/irq/handle.c:193 [inline]
handle_irq_event+0xab/0x1e0 kernel/irq/handle.c:210
handle_edge_irq+0x263/0xd10 kernel/irq/chip.c:831
generic_handle_irq_desc include/linux/irqdesc.h:173 [inline]
handle_irq arch/x86/kernel/irq.c:247 [inline]
call_irq_handler arch/x86/kernel/irq.c:259 [inline]
__common_interrupt+0xdf/0x250 arch/x86/kernel/irq.c:285
common_interrupt+0x61/0xe0 arch/x86/kernel/irq.c:278
asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:693
variable_ffs arch/x86/include/asm/bitops.h:321 [inline]
handle_softirqs+0x1da/0x8f0 kernel/softirq.c:549
__do_softirq kernel/softirq.c:595 [inline]
invoke_softirq kernel/softirq.c:435 [inline]
__irq_exit_rcu+0x109/0x170 kernel/softirq.c:662
irq_exit_rcu+0x9/0x30 kernel/softirq.c:678
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline]
sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1049
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
native_safe_halt arch/x86/include/asm/irqflags.h:48 [inline]
arch_safe_halt arch/x86/include/asm/irqflags.h:106 [inline]
acpi_safe_halt+0x1a/0x20 drivers/acpi/processor_idle.c:111
acpi_idle_enter+0xc5/0x160 drivers/acpi/processor_idle.c:699
cpuidle_enter_state+0xaa/0x4f0 drivers/cpuidle/cpuidle.c:268
cpuidle_enter+0x4e/0xa0 drivers/cpuidle/cpuidle.c:389
cpuidle_idle_call kernel/sched/idle.c:230 [inline]
do_idle+0x310/0x3f0 kernel/sched/idle.c:325
cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:423
start_secondary+0x222/0x2b0 arch/x86/kernel/smpboot.c:315
common_startup_64+0x13e/0x148

-> #2 (&tty->write_wait){-.-.}-{3:3}:
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x3a/0x60 kernel/locking/spinlock.c:162
__wake_up_common_lock kernel/sched/wait.c:105 [inline]
__wake_up+0x1c/0x60 kernel/sched/wait.c:127
tty_port_default_wakeup+0x2a/0x40 drivers/tty/tty_port.c:69
serial8250_tx_chars+0x68e/0x860 drivers/tty/serial/8250/8250_port.c:1841
serial8250_handle_irq+0x74d/0xc80 drivers/tty/serial/8250/8250_port.c:1949
serial8250_default_handle_irq+0x9a/0x210 drivers/tty/serial/8250/8250_port.c:1969
serial8250_interrupt+0x103/0x210 drivers/tty/serial/8250/8250_core.c:86
__handle_irq_event_percpu+0x229/0x7d0 kernel/irq/handle.c:158
handle_irq_event_percpu kernel/irq/handle.c:193 [inline]
handle_irq_event+0xab/0x1e0 kernel/irq/handle.c:210
handle_edge_irq+0x263/0xd10 kernel/irq/chip.c:831
generic_handle_irq_desc include/linux/irqdesc.h:173 [inline]
handle_irq arch/x86/kernel/irq.c:247 [inline]
call_irq_handler arch/x86/kernel/irq.c:259 [inline]
__common_interrupt+0xdf/0x250 arch/x86/kernel/irq.c:285
common_interrupt+0x61/0xe0 arch/x86/kernel/irq.c:278
asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:693
variable_ffs arch/x86/include/asm/bitops.h:321 [inline]
handle_softirqs+0x1da/0x8f0 kernel/softirq.c:549
__do_softirq kernel/softirq.c:595 [inline]
invoke_softirq kernel/softirq.c:435 [inline]
__irq_exit_rcu+0x109/0x170 kernel/softirq.c:662
irq_exit_rcu+0x9/0x30 kernel/softirq.c:678
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline]
sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1049
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:151 [inline]
_raw_spin_unlock_irqrestore+0x31/0x80 kernel/locking/spinlock.c:194
spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
uart_port_unlock_irqrestore include/linux/serial_core.h:786 [inline]
uart_write+0x2a4/0xb30 drivers/tty/serial/serial_core.c:636
process_output_block drivers/tty/n_tty.c:574 [inline]
n_tty_write+0x419/0x1140 drivers/tty/n_tty.c:2389
iterate_tty_write drivers/tty/tty_io.c:1015 [inline]
file_tty_write.constprop.0+0x506/0x9a0 drivers/tty/tty_io.c:1090
tty_write drivers/tty/tty_io.c:1111 [inline]
redirected_tty_write drivers/tty/tty_io.c:1134 [inline]
redirected_tty_write+0xcc/0x140 drivers/tty/tty_io.c:1114
new_sync_write fs/read_write.c:586 [inline]
vfs_write+0x5ae/0x1150 fs/read_write.c:679
ksys_write+0x12b/0x250 fs/read_write.c:731
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (&port_lock_key){-.-.}-{3:3}:
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x3a/0x60 kernel/locking/spinlock.c:162
uart_port_lock_irqsave include/linux/serial_core.h:715 [inline]
serial8250_console_write+0xb56/0x17c0 drivers/tty/serial/8250/8250_port.c:3372
console_emit_next_record kernel/printk/printk.c:3122 [inline]
console_flush_all+0x803/0xc60 kernel/printk/printk.c:3210
__console_flush_and_unlock kernel/printk/printk.c:3269 [inline]
console_unlock+0xd9/0x210 kernel/printk/printk.c:3309
vprintk_emit+0x424/0x6f0 kernel/printk/printk.c:2432
_printk+0xc8/0x100 kernel/printk/printk.c:2457
register_console+0xbfd/0x1170 kernel/printk/printk.c:4099
univ8250_console_init+0x5f/0x90 drivers/tty/serial/8250/8250_core.c:513
console_init+0x154/0x690 kernel/printk/printk.c:4292
start_kernel+0x29f/0x4d0 init/main.c:1038
x86_64_start_reservations+0x18/0x30 arch/x86/kernel/head64.c:507
x86_64_start_kernel+0xb2/0xc0 arch/x86/kernel/head64.c:488
common_startup_64+0x13e/0x148

-> #0 (console_owner){-...}-{0:0}:
check_prev_add kernel/locking/lockdep.c:3163 [inline]
check_prevs_add kernel/locking/lockdep.c:3282 [inline]
validate_chain kernel/locking/lockdep.c:3906 [inline]
__lock_acquire+0x249e/0x3c40 kernel/locking/lockdep.c:5228
lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5851
console_lock_spinning_enable+0xb0/0xd0 kernel/printk/printk.c:1924
console_emit_next_record kernel/printk/printk.c:3116 [inline]
console_flush_all+0x7ac/0xc60 kernel/printk/printk.c:3210
__console_flush_and_unlock kernel/printk/printk.c:3269 [inline]
console_unlock+0xd9/0x210 kernel/printk/printk.c:3309
vprintk_emit+0x424/0x6f0 kernel/printk/printk.c:2432
_printk+0xc8/0x100 kernel/printk/printk.c:2457
fail_dump lib/fault-inject.c:46 [inline]
should_fail_ex+0x46c/0x5b0 lib/fault-inject.c:154
__copy_to_user_inatomic include/linux/uaccess.h:132 [inline]
copy_to_user_nofault+0xac/0x180 mm/maccess.c:156
____bpf_probe_write_user kernel/trace/bpf_trace.c:348 [inline]
bpf_probe_write_user+0xaf/0xf0 kernel/trace/bpf_trace.c:326
bpf_prog_6303d92f98284ad8+0x44/0x48
bpf_dispatcher_nop_func include/linux/bpf.h:1290 [inline]
__bpf_prog_run include/linux/filter.h:701 [inline]
bpf_prog_run include/linux/filter.h:708 [inline]
__bpf_trace_run kernel/trace/bpf_trace.c:2363 [inline]
bpf_trace_run4+0x245/0x5a0 kernel/trace/bpf_trace.c:2406
__bpf_trace_sched_switch+0x13e/0x190 include/trace/events/sched.h:222
__traceiter_sched_switch+0x6c/0xc0 include/trace/events/sched.h:222
trace_sched_switch include/trace/events/sched.h:222 [inline]
__schedule+0x180b/0x5b60 kernel/sched/core.c:6757
preempt_schedule_irq+0x51/0x90 kernel/sched/core.c:7082
irqentry_exit+0x36/0x90 kernel/entry/common.c:354
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
arch_local_irq_restore arch/x86/include/asm/irqflags.h:154 [inline]
lock_acquire.part.0+0x155/0x380 kernel/locking/lockdep.c:5854
rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
rcu_read_lock include/linux/rcupdate.h:849 [inline]
__fget_files+0x46/0x3a0 fs/file.c:1049
__fget_light fs/file.c:1152 [inline]
fdget fs/file.c:1160 [inline]
fdget_pos+0x2fc/0x390 fs/file.c:1187
class_fd_pos_constructor include/linux/file.h:85 [inline]
ksys_write+0x72/0x250 fs/read_write.c:722
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

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.1.427/7673:
#0: ffffffff8e1be440 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
#0: ffffffff8e1be440 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#0: ffffffff8e1be440 (rcu_read_lock){....}-{1:3}, at: __fget_files+0x40/0x3a0 fs/file.c:1049
#1: ffff8880b863ec18 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x29/0x130 kernel/sched/core.c:598
#2: ffffffff8e1be440 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
#2: ffffffff8e1be440 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#2: ffffffff8e1be440 (rcu_read_lock){....}-{1:3}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2362 [inline]
#2: ffffffff8e1be440 (rcu_read_lock){....}-{1:3}, at: bpf_trace_run4+0x1d6/0x5a0 kernel/trace/bpf_trace.c:2406
#3: ffffffff8e1abb80 (console_lock){+.+.}-{0:0}, at: _printk+0xc8/0x100 kernel/printk/printk.c:2457
#4: ffffffff8e1abbf0 (console_srcu){....}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:342 [inline]
#4: ffffffff8e1abbf0 (console_srcu){....}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:304 [inline]
#4: ffffffff8e1abbf0 (console_srcu){....}-{0:0}, at: console_srcu_read_lock kernel/printk/printk.c:288 [inline]
#4: ffffffff8e1abbf0 (console_srcu){....}-{0:0}, at: console_flush_all+0x159/0xc60 kernel/printk/printk.c:3187

stack backtrace:
CPU: 0 UID: 0 PID: 7673 Comm: syz.1.427 Not tainted 6.13.0-syzkaller-gc4b9570cfb63-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
print_circular_bug+0x490/0x760 kernel/locking/lockdep.c:2076
check_noncircular+0x31a/0x400 kernel/locking/lockdep.c:2208
check_prev_add kernel/locking/lockdep.c:3163 [inline]
check_prevs_add kernel/locking/lockdep.c:3282 [inline]
validate_chain kernel/locking/lockdep.c:3906 [inline]
__lock_acquire+0x249e/0x3c40 kernel/locking/lockdep.c:5228
lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5851
console_lock_spinning_enable+0xb0/0xd0 kernel/printk/printk.c:1924
console_emit_next_record kernel/printk/printk.c:3116 [inline]
console_flush_all+0x7ac/0xc60 kernel/printk/printk.c:3210
__console_flush_and_unlock kernel/printk/printk.c:3269 [inline]
console_unlock+0xd9/0x210 kernel/printk/printk.c:3309
vprintk_emit+0x424/0x6f0 kernel/printk/printk.c:2432
_printk+0xc8/0x100 kernel/printk/printk.c:2457
fail_dump lib/fault-inject.c:46 [inline]
should_fail_ex+0x46c/0x5b0 lib/fault-inject.c:154
__copy_to_user_inatomic include/linux/uaccess.h:132 [inline]
copy_to_user_nofault+0xac/0x180 mm/maccess.c:156
____bpf_probe_write_user kernel/trace/bpf_trace.c:348 [inline]
bpf_probe_write_user+0xaf/0xf0 kernel/trace/bpf_trace.c:326
bpf_prog_6303d92f98284ad8+0x44/0x48
bpf_dispatcher_nop_func include/linux/bpf.h:1290 [inline]
__bpf_prog_run include/linux/filter.h:701 [inline]
bpf_prog_run include/linux/filter.h:708 [inline]
__bpf_trace_run kernel/trace/bpf_trace.c:2363 [inline]
bpf_trace_run4+0x245/0x5a0 kernel/trace/bpf_trace.c:2406
__bpf_trace_sched_switch+0x13e/0x190 include/trace/events/sched.h:222
__traceiter_sched_switch+0x6c/0xc0 include/trace/events/sched.h:222
trace_sched_switch include/trace/events/sched.h:222 [inline]
__schedule+0x180b/0x5b60 kernel/sched/core.c:6757
preempt_schedule_irq+0x51/0x90 kernel/sched/core.c:7082
irqentry_exit+0x36/0x90 kernel/entry/common.c:354
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:lock_acquire.part.0+0x155/0x380 kernel/locking/lockdep.c:5816
Code: b8 ff ff ff ff 65 0f c1 05 00 a8 8b 7e 83 f8 01 0f 85 d0 01 00 00 9c 58 f6 c4 02 0f 85 e5 01 00 00 48 85 ed 0f 85 b6 01 00 00 <48> b8 00 00 00 00 00 fc ff df 48 01 c3 48 c7 03 00 00 00 00 48 c7
RSP: 0018:ffffc900046c7d28 EFLAGS: 00000206
RAX: 0000000000000046 RBX: 1ffff920008d8fa6 RCX: 00000000d439196c
RDX: 0000000000000001 RSI: ffffffff8b6cdcc0 RDI: ffffffff8bd2c740
RBP: 0000000000000200 R08: 0000000000000000 R09: fffffbfff2dd0d98
R10: ffffffff96e86cc7 R11: 0000000000000000 R12: 0000000000000000
R13: ffffffff8e1be440 R14: 0000000000000000 R15: 0000000000000000
rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
rcu_read_lock include/linux/rcupdate.h:849 [inline]
__fget_files+0x46/0x3a0 fs/file.c:1049
__fget_light fs/file.c:1152 [inline]
fdget fs/file.c:1160 [inline]
fdget_pos+0x2fc/0x390 fs/file.c:1187
class_fd_pos_constructor include/linux/file.h:85 [inline]
ksys_write+0x72/0x250 fs/read_write.c:722
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f751a1847df
Code: 89 54 24 18 48 89 74 24 10 89 7c 24 08 e8 f9 92 02 00 48 8b 54 24 18 48 8b 74 24 10 41 89 c0 8b 7c 24 08 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 31 44 89 c7 48 89 44 24 08 e8 4c 93 02 00 48
RSP: 002b:00007f751b083030 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f751a1847df
RDX: 0000000000000001 RSI: 00007f751b0830a0 RDI: 0000000000000005
RBP: 00007f751b083090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000001
R13: 0000000000000000 R14: 00007f751a375fa0 R15: 00007fff4f6d3d38
</TASK>
CPU: 0 UID: 0 PID: 7673 Comm: syz.1.427 Not tainted 6.13.0-syzkaller-gc4b9570cfb63-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
fail_dump lib/fault-inject.c:53 [inline]
should_fail_ex+0x497/0x5b0 lib/fault-inject.c:154
__copy_to_user_inatomic include/linux/uaccess.h:132 [inline]
copy_to_user_nofault+0xac/0x180 mm/maccess.c:156
____bpf_probe_write_user kernel/trace/bpf_trace.c:348 [inline]
bpf_probe_write_user+0xaf/0xf0 kernel/trace/bpf_trace.c:326
bpf_prog_6303d92f98284ad8+0x44/0x48
bpf_dispatcher_nop_func include/linux/bpf.h:1290 [inline]
__bpf_prog_run include/linux/filter.h:701 [inline]
bpf_prog_run include/linux/filter.h:708 [inline]
__bpf_trace_run kernel/trace/bpf_trace.c:2363 [inline]
bpf_trace_run4+0x245/0x5a0 kernel/trace/bpf_trace.c:2406
__bpf_trace_sched_switch+0x13e/0x190 include/trace/events/sched.h:222
__traceiter_sched_switch+0x6c/0xc0 include/trace/events/sched.h:222
trace_sched_switch include/trace/events/sched.h:222 [inline]
__schedule+0x180b/0x5b60 kernel/sched/core.c:6757
preempt_schedule_irq+0x51/0x90 kernel/sched/core.c:7082
irqentry_exit+0x36/0x90 kernel/entry/common.c:354
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:lock_acquire.part.0+0x155/0x380 kernel/locking/lockdep.c:5816
Code: b8 ff ff ff ff 65 0f c1 05 00 a8 8b 7e 83 f8 01 0f 85 d0 01 00 00 9c 58 f6 c4 02 0f 85 e5 01 00 00 48 85 ed 0f 85 b6 01 00 00 <48> b8 00 00 00 00 00 fc ff df 48 01 c3 48 c7 03 00 00 00 00 48 c7
RSP: 0018:ffffc900046c7d28 EFLAGS: 00000206
RAX: 0000000000000046 RBX: 1ffff920008d8fa6 RCX: 00000000d439196c
RDX: 0000000000000001 RSI: ffffffff8b6cdcc0 RDI: ffffffff8bd2c740
RBP: 0000000000000200 R08: 0000000000000000 R09: fffffbfff2dd0d98
R10: ffffffff96e86cc7 R11: 0000000000000000 R12: 0000000000000000
R13: ffffffff8e1be440 R14: 0000000000000000 R15: 0000000000000000
rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
rcu_read_lock include/linux/rcupdate.h:849 [inline]
__fget_files+0x46/0x3a0 fs/file.c:1049
__fget_light fs/file.c:1152 [inline]
fdget fs/file.c:1160 [inline]
fdget_pos+0x2fc/0x390 fs/file.c:1187
class_fd_pos_constructor include/linux/file.h:85 [inline]
ksys_write+0x72/0x250 fs/read_write.c:722
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f751a1847df
Code: 89 54 24 18 48 89 74 24 10 89 7c 24 08 e8 f9 92 02 00 48 8b 54 24 18 48 8b 74 24 10 41 89 c0 8b 7c 24 08 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 31 44 89 c7 48 89 44 24 08 e8 4c 93 02 00 48
RSP: 002b:00007f751b083030 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f751a1847df
RDX: 0000000000000001 RSI: 00007f751b0830a0 RDI: 0000000000000005
RBP: 00007f751b083090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000001
R13: 0000000000000000 R14: 00007f751a375fa0 R15: 00007fff4f6d3d38
</TASK>
----------------
Code disassembly (best guess):
0: b8 ff ff ff ff mov $0xffffffff,%eax
5: 65 0f c1 05 00 a8 8b xadd %eax,%gs:0x7e8ba800(%rip) # 0x7e8ba80d
c: 7e
d: 83 f8 01 cmp $0x1,%eax
10: 0f 85 d0 01 00 00 jne 0x1e6
16: 9c pushf
17: 58 pop %rax
18: f6 c4 02 test $0x2,%ah
1b: 0f 85 e5 01 00 00 jne 0x206
21: 48 85 ed test %rbp,%rbp
24: 0f 85 b6 01 00 00 jne 0x1e0
* 2a: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax <-- trapping instruction
31: fc ff df
34: 48 01 c3 add %rax,%rbx
37: 48 c7 03 00 00 00 00 movq $0x0,(%rbx)
3e: 48 rex.W
3f: c7 .byte 0xc7

Tested on:

commit: c4b9570c Merge tag 'audit-pr-20250121' of git://git.ke..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=135a1824580000
kernel config: https://syzkaller.appspot.com/x/.config?x=899f38f532606c8e
dashboard link: https://syzkaller.appspot.com/bug?extid=622acb507894a48b2ce9
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
patch: https://syzkaller.appspot.com/x/patch.diff?x=1343c5df980000

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