netlink: 4 bytes leftover after parsing attributes in process `syz-executor.0'. ============================================ WARNING: possible recursive locking detected 4.19.211-syzkaller #0 Not tainted -------------------------------------------- syz-executor.2/20383 is trying to acquire lock: 00000000109dec35 (&port_lock_key){-.-.}, at: uart_write+0x1ce/0x6f0 drivers/tty/serial/serial_core.c:591 but task is already holding lock: 00000000109dec35 (&port_lock_key){-.-.}, at: serial8250_handle_irq.part.0+0x21/0x3d0 drivers/tty/serial/8250/8250_port.c:1876 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&port_lock_key); lock(&port_lock_key); *** DEADLOCK *** May be due to missing lock nesting notation 3 locks held by syz-executor.2/20383: #0: 00000000149035bc (&(&i->lock)->rlock){-.-.}, at: spin_lock include/linux/spinlock.h:329 [inline] #0: 00000000149035bc (&(&i->lock)->rlock){-.-.}, at: serial8250_interrupt+0x3a/0x240 drivers/tty/serial/8250/8250_core.c:115 #1: 00000000109dec35 (&port_lock_key){-.-.}, at: serial8250_handle_irq.part.0+0x21/0x3d0 drivers/tty/serial/8250/8250_port.c:1876 #2: 000000004f13be44 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref+0x1d/0x80 drivers/tty/tty_ldisc.c:293 stack backtrace: CPU: 1 PID: 20383 Comm: syz-executor.2 Not tainted 4.19.211-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1fc/0x2ef lib/dump_stack.c:118 print_deadlock_bug kernel/locking/lockdep.c:1764 [inline] check_deadlock kernel/locking/lockdep.c:1808 [inline] validate_chain kernel/locking/lockdep.c:2404 [inline] __lock_acquire.cold+0x121/0x57e kernel/locking/lockdep.c:3416 lock_acquire+0x170/0x3c0 kernel/locking/lockdep.c:3908 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x8c/0xc0 kernel/locking/spinlock.c:152 uart_write+0x1ce/0x6f0 drivers/tty/serial/serial_core.c:591 n_hdlc_send_frames+0x278/0x470 drivers/tty/n_hdlc.c:403 n_hdlc_tty_wakeup+0xa0/0xc0 drivers/tty/n_hdlc.c:479 tty_wakeup+0xd4/0x110 drivers/tty/tty_io.c:534 tty_port_default_wakeup+0x26/0x40 drivers/tty/tty_port.c:50 serial8250_tx_chars+0x490/0xaf0 drivers/tty/serial/8250/8250_port.c:1813 serial8250_handle_irq.part.0+0x31f/0x3d0 drivers/tty/serial/8250/8250_port.c:1900 serial8250_handle_irq drivers/tty/serial/8250/8250_port.c:1873 [inline] serial8250_default_handle_irq+0xae/0x220 drivers/tty/serial/8250/8250_port.c:1916 serial8250_interrupt+0x101/0x240 drivers/tty/serial/8250/8250_core.c:125 __handle_irq_event_percpu+0x27e/0x8e0 kernel/irq/handle.c:149 handle_irq_event_percpu kernel/irq/handle.c:189 [inline] handle_irq_event+0x102/0x290 kernel/irq/handle.c:206 handle_edge_irq+0x260/0xcf0 kernel/irq/chip.c:800 generic_handle_irq_desc include/linux/irqdesc.h:155 [inline] handle_irq+0x35/0x50 arch/x86/kernel/irq_64.c:87 do_IRQ+0x93/0x1c0 arch/x86/kernel/irq.c:246 common_interrupt+0xf/0xf arch/x86/entry/entry_64.S:670 RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:169 [inline] RIP: 0010:_raw_spin_unlock_irq+0x50/0x80 kernel/locking/spinlock.c:192 Code: c0 98 82 f1 89 48 ba 00 00 00 00 00 fc ff df 48 c1 e8 03 80 3c 10 00 75 31 48 83 3d 01 31 d8 01 00 74 25 fb 66 0f 1f 44 00 00 01 00 00 00 e8 26 1b 28 f9 65 8b 05 9f 8d e8 77 85 c0 74 02 5d RSP: 0018:ffff888050c37b10 EFLAGS: 00000286 ORIG_RAX: ffffffffffffffd2 RAX: 1ffffffff13e3053 RBX: ffff888096a323c0 RCX: 0000000000000000 RDX: dffffc0000000000 RSI: 0000000000000001 RDI: ffff888096a32c44 RBP: ffff8880ba12b0c0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880ba12b0c0 R13: ffff8880b4b36180 R14: 0000000000000000 R15: 0000000000000001 finish_lock_switch kernel/sched/core.c:2578 [inline] finish_task_switch+0x146/0x760 kernel/sched/core.c:2678 context_switch kernel/sched/core.c:2831 [inline] __schedule+0x88f/0x2040 kernel/sched/core.c:3517 schedule+0x8d/0x1b0 kernel/sched/core.c:3561 freezable_schedule include/linux/freezer.h:172 [inline] do_nanosleep+0x264/0x6c0 kernel/time/hrtimer.c:1755 hrtimer_nanosleep+0x24d/0x570 kernel/time/hrtimer.c:1809 common_nsleep+0x23/0x30 kernel/time/posix-timers.c:1204 __do_sys_clock_nanosleep kernel/time/posix-timers.c:1231 [inline] __se_sys_clock_nanosleep+0x261/0x360 kernel/time/posix-timers.c:1209 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7f79302ab361 Code: 24 0c 89 3c 24 48 89 4c 24 18 e8 aa e7 ff ff 4c 8b 54 24 18 48 8b 54 24 10 41 89 c0 8b 74 24 0c 8b 3c 24 b8 e6 00 00 00 0f 05 <44> 89 c7 48 89 04 24 e8 e3 e7 ff ff 48 8b 04 24 eb 97 66 2e 0f 1f RSP: 002b:00007fff10c693d0 EFLAGS: 00000293 ORIG_RAX: 00000000000000e6 RAX: ffffffffffffffda RBX: 000000000000025b RCX: 00007f79302ab361 RDX: 00007fff10c69410 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 00007fff10c6949c R08: 0000000000000000 R09: 000000927166fb3a R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000032 R13: 000000000008ac87 R14: 0000000000000004 R15: 00007fff10c69500 ---------------- Code disassembly (best guess), 5 bytes skipped: 0: 48 ba 00 00 00 00 00 movabs $0xdffffc0000000000,%rdx 7: fc ff df a: 48 c1 e8 03 shr $0x3,%rax e: 80 3c 10 00 cmpb $0x0,(%rax,%rdx,1) 12: 75 31 jne 0x45 14: 48 83 3d 01 31 d8 01 cmpq $0x0,0x1d83101(%rip) # 0x1d8311d 1b: 00 1c: 74 25 je 0x43 1e: fb sti 1f: 66 0f 1f 44 00 00 nopw 0x0(%rax,%rax,1) * 25: bf 01 00 00 00 mov $0x1,%edi <-- trapping instruction 2a: e8 26 1b 28 f9 callq 0xf9281b55 2f: 65 8b 05 9f 8d e8 77 mov %gs:0x77e88d9f(%rip),%eax # 0x77e88dd5 36: 85 c0 test %eax,%eax 38: 74 02 je 0x3c 3a: 5d pop %rbp