Re: [syzbot] possible deadlock in snd_timer_interrupt (2)

Re: [syzbot] possible deadlock in snd_timer_interrupt (2)

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit:    1f2cfdd349b7 printk: Fix incorrect __user type in proc_doi..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=146fce24700000
kernel config:  https://syzkaller.appspot.com/x/.config?x=b4a89edfcc8f7c74
dashboard link: https://syzkaller.appspot.com/bug?extid=1ee0910eca9c94f71f25
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1007e462700000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+1ee0910eca9c94f71f25@syzkaller.appspotmail.com

========================================================
WARNING: possible irq lock inversion dependency detected
5.17.0-rc2-syzkaller-00071-g1f2cfdd349b7 #0 Not tainted
--------------------------------------------------------
syz-executor.3/4250 just changed the state of lock:
ffff88814a62e148 (&timer->lock){..-.}-{2:2}, at: snd_timer_interrupt.part.0+0x34/0xcf0 sound/core/timer.c:856
but this lock took another, SOFTIRQ-READ-unsafe lock in the past:
 (tasklist_lock){.+.+}-{2:2}


and interrupts could create inverse lock ordering between them.


other info that might help us debug this:
Chain exists of:
  &timer->lock --> &new->fa_lock --> tasklist_lock

 Possible interrupt unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(tasklist_lock);
                               local_irq_disable();
                               lock(&timer->lock);
                               lock(&new->fa_lock);
  <Interrupt>
    lock(&timer->lock);

 *** DEADLOCK ***

2 locks held by syz-executor.3/4250:
 #0: ffff88807efef828 (&mm->mmap_lock#2){++++}-{3:3}, at: __might_fault+0xa1/0x170 mm/memory.c:5271
 #1: ffffc90000dc0d70 ((&priv->tlist)){+.-.}-{0:0}, at: lockdep_copy_map include/linux/lockdep.h:35 [inline]
 #1: ffffc90000dc0d70 ((&priv->tlist)){+.-.}-{0:0}, at: call_timer_fn+0xd5/0x6b0 kernel/time/timer.c:1411

the shortest dependencies between 2nd lock and 1st lock:
   -> (tasklist_lock){.+.+}-{2:2} {
      HARDIRQ-ON-R at:
                          lock_acquire kernel/locking/lockdep.c:5639 [inline]
                          lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
                          __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline]
                          _raw_read_lock+0x5b/0x70 kernel/locking/spinlock.c:228
                          do_wait+0x284/0xce0 kernel/exit.c:1518
                          kernel_wait+0x9c/0x150 kernel/exit.c:1708
                          call_usermodehelper_exec_sync kernel/umh.c:139 [inline]
                          call_usermodehelper_exec_work+0xf5/0x180 kernel/umh.c:166
                          process_one_work+0x9ac/0x1650 kernel/workqueue.c:2307
                          worker_thread+0x657/0x1110 kernel/workqueue.c:2454
                          kthread+0x2e9/0x3a0 kernel/kthread.c:377
                          ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
      SOFTIRQ-ON-R at:
                          lock_acquire kernel/locking/lockdep.c:5639 [inline]
                          lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
                          __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline]
                          _raw_read_lock+0x5b/0x70 kernel/locking/spinlock.c:228
                          do_wait+0x284/0xce0 kernel/exit.c:1518
                          kernel_wait+0x9c/0x150 kernel/exit.c:1708
                          call_usermodehelper_exec_sync kernel/umh.c:139 [inline]
                          call_usermodehelper_exec_work+0xf5/0x180 kernel/umh.c:166
                          process_one_work+0x9ac/0x1650 kernel/workqueue.c:2307
                          worker_thread+0x657/0x1110 kernel/workqueue.c:2454
                          kthread+0x2e9/0x3a0 kernel/kthread.c:377
                          ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
      INITIAL USE at:
                         lock_acquire kernel/locking/lockdep.c:5639 [inline]
                         lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
                         __raw_write_lock_irq include/linux/rwlock_api_smp.h:195 [inline]
                         _raw_write_lock_irq+0x32/0x50 kernel/locking/spinlock.c:326
                         copy_process+0x47da/0x7300 kernel/fork.c:2284
                         kernel_clone+0xe7/0xab0 kernel/fork.c:2555
                         kernel_thread+0xb5/0xf0 kernel/fork.c:2607
                         rest_init+0x23/0x3e0 init/main.c:690
                         start_kernel+0x47a/0x49b init/main.c:1138
                         secondary_startup_64_no_verify+0xc3/0xcb
      INITIAL READ USE at:
                              lock_acquire kernel/locking/lockdep.c:5639 [inline]
                              lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
                              __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline]
                              _raw_read_lock+0x5b/0x70 kernel/locking/spinlock.c:228
                              do_wait+0x284/0xce0 kernel/exit.c:1518
                              kernel_wait+0x9c/0x150 kernel/exit.c:1708
                              call_usermodehelper_exec_sync kernel/umh.c:139 [inline]
                              call_usermodehelper_exec_work+0xf5/0x180 kernel/umh.c:166
                              process_one_work+0x9ac/0x1650 kernel/workqueue.c:2307
                              worker_thread+0x657/0x1110 kernel/workqueue.c:2454
                              kthread+0x2e9/0x3a0 kernel/kthread.c:377
                              ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
    }
    ... key      at: [<ffffffff8b80a098>] tasklist_lock+0x18/0x40
    ... acquired at:
   __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline]
   _raw_read_lock+0x5b/0x70 kernel/locking/spinlock.c:228
   send_sigio+0xab/0x380 fs/fcntl.c:810
   kill_fasync_rcu fs/fcntl.c:1021 [inline]
   kill_fasync fs/fcntl.c:1035 [inline]
   kill_fasync+0x1f8/0x470 fs/fcntl.c:1028
   sock_wake_async+0xd2/0x160 net/socket.c:1372
   sk_wake_async include/net/sock.h:2444 [inline]
   sk_wake_async include/net/sock.h:2440 [inline]
   sock_def_readable+0x349/0x4e0 net/core/sock.c:3149
   unix_dgram_sendmsg+0xf30/0x1a10 net/unix/af_unix.c:2029
   sock_sendmsg_nosec net/socket.c:705 [inline]
   sock_sendmsg+0xcf/0x120 net/socket.c:725
   ____sys_sendmsg+0x331/0x810 net/socket.c:2413
   ___sys_sendmsg+0xf3/0x170 net/socket.c:2467
   __sys_sendmmsg+0x195/0x470 net/socket.c:2553
   __do_sys_sendmmsg net/socket.c:2582 [inline]
   __se_sys_sendmmsg net/socket.c:2579 [inline]
   __x64_sys_sendmmsg+0x99/0x100 net/socket.c:2579
   do_syscall_x64 arch/x86/entry/common.c:50 [inline]
   do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
   entry_SYSCALL_64_after_hwframe+0x44/0xae

  -> (&f->f_owner.lock){....}-{2:2} {
     INITIAL USE at:
                       lock_acquire kernel/locking/lockdep.c:5639 [inline]
                       lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
                       __raw_write_lock_irq include/linux/rwlock_api_smp.h:195 [inline]
                       _raw_write_lock_irq+0x32/0x50 kernel/locking/spinlock.c:326
                       f_modown+0x2a/0x390 fs/fcntl.c:91
                       __f_setown fs/fcntl.c:110 [inline]
                       f_setown+0xd7/0x230 fs/fcntl.c:138
                       sock_ioctl+0x37e/0x640 net/socket.c:1182
                       vfs_ioctl fs/ioctl.c:51 [inline]
                       __do_sys_ioctl fs/ioctl.c:874 [inline]
                       __se_sys_ioctl fs/ioctl.c:860 [inline]
                       __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860
                       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
                       do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
                       entry_SYSCALL_64_after_hwframe+0x44/0xae
     INITIAL READ USE at:
                            lock_acquire kernel/locking/lockdep.c:5639 [inline]
                            lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
                            __raw_read_lock_irqsave include/linux/rwlock_api_smp.h:160 [inline]
                            _raw_read_lock_irqsave+0x70/0x90 kernel/locking/spinlock.c:236
                            send_sigio+0x24/0x380 fs/fcntl.c:796
                            kill_fasync_rcu fs/fcntl.c:1021 [inline]
                            kill_fasync fs/fcntl.c:1035 [inline]
                            kill_fasync+0x1f8/0x470 fs/fcntl.c:1028
                            snd_timer_user_ccallback+0x298/0x330 sound/core/timer.c:1386
                            snd_timer_notify1+0x11c/0x3b0 sound/core/timer.c:516
                            snd_timer_start1+0x4d4/0x800 sound/core/timer.c:578
                            snd_timer_start sound/core/timer.c:696 [inline]
                            snd_timer_start sound/core/timer.c:689 [inline]
                            snd_timer_user_start.isra.0+0x1e3/0x260 sound/core/timer.c:1984
                            __snd_timer_user_ioctl.isra.0+0xda8/0x2490 sound/core/timer.c:2107
                            snd_timer_user_ioctl+0x77/0xb0 sound/core/timer.c:2128
                            vfs_ioctl fs/ioctl.c:51 [inline]
                            __do_sys_ioctl fs/ioctl.c:874 [inline]
                            __se_sys_ioctl fs/ioctl.c:860 [inline]
                            __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860
                            do_syscall_x64 arch/x86/entry/common.c:50 [inline]
                            do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
                            entry_SYSCALL_64_after_hwframe+0x44/0xae
   }
   ... key      at: [<ffffffff9057ea40>] __key.5+0x0/0x40
   ... acquired at:
   __raw_read_lock_irqsave include/linux/rwlock_api_smp.h:160 [inline]
   _raw_read_lock_irqsave+0x70/0x90 kernel/locking/spinlock.c:236
   send_sigio+0x24/0x380 fs/fcntl.c:796
   kill_fasync_rcu fs/fcntl.c:1021 [inline]
   kill_fasync fs/fcntl.c:1035 [inline]
   kill_fasync+0x1f8/0x470 fs/fcntl.c:1028
   snd_timer_user_ccallback+0x298/0x330 sound/core/timer.c:1386
   snd_timer_notify1+0x11c/0x3b0 sound/core/timer.c:516
   snd_timer_start1+0x4d4/0x800 sound/core/timer.c:578
   snd_timer_start sound/core/timer.c:696 [inline]
   snd_timer_start sound/core/timer.c:689 [inline]
   snd_timer_user_start.isra.0+0x1e3/0x260 sound/core/timer.c:1984
   __snd_timer_user_ioctl.isra.0+0xda8/0x2490 sound/core/timer.c:2107
   snd_timer_user_ioctl+0x77/0xb0 sound/core/timer.c:2128
   vfs_ioctl fs/ioctl.c:51 [inline]
   __do_sys_ioctl fs/ioctl.c:874 [inline]
   __se_sys_ioctl fs/ioctl.c:860 [inline]
   __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860
   do_syscall_x64 arch/x86/entry/common.c:50 [inline]
   do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
   entry_SYSCALL_64_after_hwframe+0x44/0xae

 -> (&new->fa_lock){....}-{2:2} {
    INITIAL USE at:
                     lock_acquire kernel/locking/lockdep.c:5639 [inline]
                     lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
                     __raw_write_lock_irq include/linux/rwlock_api_smp.h:195 [inline]
                     _raw_write_lock_irq+0x32/0x50 kernel/locking/spinlock.c:326
                     fasync_remove_entry+0xb6/0x1f0 fs/fcntl.c:891
                     fasync_helper+0x9e/0xb0 fs/fcntl.c:994
                     __fput+0x846/0x9f0 fs/file_table.c:308
                     task_work_run+0xdd/0x1a0 kernel/task_work.c:164
                     tracehook_notify_resume include/linux/tracehook.h:188 [inline]
                     exit_to_user_mode_loop kernel/entry/common.c:175 [inline]
                     exit_to_user_mode_prepare+0x27e/0x290 kernel/entry/common.c:207
                     __syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline]
                     syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:300
                     do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86
                     entry_SYSCALL_64_after_hwframe+0x44/0xae
    INITIAL READ USE at:
                          lock_acquire kernel/locking/lockdep.c:5639 [inline]
                          lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
                          __raw_read_lock_irqsave include/linux/rwlock_api_smp.h:160 [inline]
                          _raw_read_lock_irqsave+0x70/0x90 kernel/locking/spinlock.c:236
                          kill_fasync_rcu fs/fcntl.c:1014 [inline]
                          kill_fasync fs/fcntl.c:1035 [inline]
                          kill_fasync+0x136/0x470 fs/fcntl.c:1028
                          snd_timer_user_ccallback+0x298/0x330 sound/core/timer.c:1386
                          snd_timer_notify1+0x11c/0x3b0 sound/core/timer.c:516
                          snd_timer_start1+0x4d4/0x800 sound/core/timer.c:578
                          snd_timer_start sound/core/timer.c:696 [inline]
                          snd_timer_start sound/core/timer.c:689 [inline]
                          snd_timer_user_start.isra.0+0x1e3/0x260 sound/core/timer.c:1984
                          __snd_timer_user_ioctl.isra.0+0xda8/0x2490 sound/core/timer.c:2107
                          snd_timer_user_ioctl+0x77/0xb0 sound/core/timer.c:2128
                          vfs_ioctl fs/ioctl.c:51 [inline]
                          __do_sys_ioctl fs/ioctl.c:874 [inline]
                          __se_sys_ioctl fs/ioctl.c:860 [inline]
                          __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860
                          do_syscall_x64 arch/x86/entry/common.c:50 [inline]
                          do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
                          entry_SYSCALL_64_after_hwframe+0x44/0xae
  }
  ... key      at: [<ffffffff9057f820>] __key.0+0x0/0x40
  ... acquired at:
   __raw_read_lock_irqsave include/linux/rwlock_api_smp.h:160 [inline]
   _raw_read_lock_irqsave+0x70/0x90 kernel/locking/spinlock.c:236
   kill_fasync_rcu fs/fcntl.c:1014 [inline]
   kill_fasync fs/fcntl.c:1035 [inline]
   kill_fasync+0x136/0x470 fs/fcntl.c:1028
   snd_timer_user_ccallback+0x298/0x330 sound/core/timer.c:1386
   snd_timer_notify1+0x11c/0x3b0 sound/core/timer.c:516
   snd_timer_start1+0x4d4/0x800 sound/core/timer.c:578
   snd_timer_start sound/core/timer.c:696 [inline]
   snd_timer_start sound/core/timer.c:689 [inline]
   snd_timer_user_start.isra.0+0x1e3/0x260 sound/core/timer.c:1984
   __snd_timer_user_ioctl.isra.0+0xda8/0x2490 sound/core/timer.c:2107
   snd_timer_user_ioctl+0x77/0xb0 sound/core/timer.c:2128
   vfs_ioctl fs/ioctl.c:51 [inline]
   __do_sys_ioctl fs/ioctl.c:874 [inline]
   __se_sys_ioctl fs/ioctl.c:860 [inline]
   __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860
   do_syscall_x64 arch/x86/entry/common.c:50 [inline]
   do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
   entry_SYSCALL_64_after_hwframe+0x44/0xae

-> (&timer->lock){..-.}-{2:2} {
   IN-SOFTIRQ-W at:
                    lock_acquire kernel/locking/lockdep.c:5639 [inline]
                    lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
                    __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
                    _raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:162
                    snd_timer_interrupt.part.0+0x34/0xcf0 sound/core/timer.c:856
                    snd_timer_interrupt sound/core/timer.c:1154 [inline]
                    snd_timer_s_function+0x14b/0x200 sound/core/timer.c:1154
                    call_timer_fn+0x1a5/0x6b0 kernel/time/timer.c:1421
                    expire_timers kernel/time/timer.c:1466 [inline]
                    __run_timers.part.0+0x67c/0xa30 kernel/time/timer.c:1734
                    __run_timers kernel/time/timer.c:1715 [inline]
                    run_timer_softirq+0xb3/0x1d0 kernel/time/timer.c:1747
                    __do_softirq+0x29b/0x9c2 kernel/softirq.c:558
                    invoke_softirq kernel/softirq.c:432 [inline]
                    __irq_exit_rcu+0x123/0x180 kernel/softirq.c:637
                    irq_exit_rcu+0x5/0x20 kernel/softirq.c:649
                    sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1097
                    asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638
                    kasan_check_range+0x0/0x180 mm/kasan/generic.c:349
                    instrument_atomic_read include/linux/instrumented.h:71 [inline]
                    test_bit include/asm-generic/bitops/instrumented-non-atomic.h:134 [inline]
                    cpumask_test_cpu include/linux/cpumask.h:379 [inline]
                    cpu_online include/linux/cpumask.h:921 [inline]
                    trace_lock_release include/trace/events/lock.h:58 [inline]
                    lock_release+0xa1/0x720 kernel/locking/lockdep.c:5650
                    __might_fault mm/memory.c:5272 [inline]
                    __might_fault+0x142/0x170 mm/memory.c:5257
                    _copy_from_user+0x27/0x180 lib/usercopy.c:13
                    copy_from_user include/linux/uaccess.h:192 [inline]
                    snd_seq_oss_write+0x38b/0x780 sound/core/seq/oss/seq_oss_rw.c:93
                    odev_write+0x55/0x90 sound/core/seq/oss/seq_oss.c:168
                    vfs_write+0x28e/0xae0 fs/read_write.c:588
                    ksys_write+0x12d/0x250 fs/read_write.c:643
                    do_syscall_x64 arch/x86/entry/common.c:50 [inline]
                    do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
                    entry_SYSCALL_64_after_hwframe+0x44/0xae
   INITIAL USE at:
                   lock_acquire kernel/locking/lockdep.c:5639 [inline]
                   lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
                   __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
                   _raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:162
                   snd_timer_resolution+0x55/0x100 sound/core/timer.c:489
                   snd_timer_user_params.isra.0+0x18e/0x8c0 sound/core/timer.c:1851
                   __snd_timer_user_ioctl.isra.0+0x1020/0x2490 sound/core/timer.c:2100
                   snd_timer_user_ioctl+0x77/0xb0 sound/core/timer.c:2128
                   vfs_ioctl fs/ioctl.c:51 [inline]
                   __do_sys_ioctl fs/ioctl.c:874 [inline]
                   __se_sys_ioctl fs/ioctl.c:860 [inline]
                   __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860
                   do_syscall_x64 arch/x86/entry/common.c:50 [inline]
                   do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
                   entry_SYSCALL_64_after_hwframe+0x44/0xae
 }
 ... key      at: [<ffffffff9087d3c0>] __key.12+0x0/0x40
 ... acquired at:
   mark_usage kernel/locking/lockdep.c:4500 [inline]
   __lock_acquire+0x11d2/0x5470 kernel/locking/lockdep.c:4981
   lock_acquire kernel/locking/lockdep.c:5639 [inline]
   lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
   __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
   _raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:162
   snd_timer_interrupt.part.0+0x34/0xcf0 sound/core/timer.c:856
   snd_timer_interrupt sound/core/timer.c:1154 [inline]
   snd_timer_s_function+0x14b/0x200 sound/core/timer.c:1154
   call_timer_fn+0x1a5/0x6b0 kernel/time/timer.c:1421
   expire_timers kernel/time/timer.c:1466 [inline]
   __run_timers.part.0+0x67c/0xa30 kernel/time/timer.c:1734
   __run_timers kernel/time/timer.c:1715 [inline]
   run_timer_softirq+0xb3/0x1d0 kernel/time/timer.c:1747
   __do_softirq+0x29b/0x9c2 kernel/softirq.c:558
   invoke_softirq kernel/softirq.c:432 [inline]
   __irq_exit_rcu+0x123/0x180 kernel/softirq.c:637
   irq_exit_rcu+0x5/0x20 kernel/softirq.c:649
   sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1097
   asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638
   kasan_check_range+0x0/0x180 mm/kasan/generic.c:349
   instrument_atomic_read include/linux/instrumented.h:71 [inline]
   test_bit include/asm-generic/bitops/instrumented-non-atomic.h:134 [inline]
   cpumask_test_cpu include/linux/cpumask.h:379 [inline]
   cpu_online include/linux/cpumask.h:921 [inline]
   trace_lock_release include/trace/events/lock.h:58 [inline]
   lock_release+0xa1/0x720 kernel/locking/lockdep.c:5650
   __might_fault mm/memory.c:5272 [inline]
   __might_fault+0x142/0x170 mm/memory.c:5257
   _copy_from_user+0x27/0x180 lib/usercopy.c:13
   copy_from_user include/linux/uaccess.h:192 [inline]
   snd_seq_oss_write+0x38b/0x780 sound/core/seq/oss/seq_oss_rw.c:93
   odev_write+0x55/0x90 sound/core/seq/oss/seq_oss.c:168
   vfs_write+0x28e/0xae0 fs/read_write.c:588
   ksys_write+0x12d/0x250 fs/read_write.c:643
   do_syscall_x64 arch/x86/entry/common.c:50 [inline]
   do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
   entry_SYSCALL_64_after_hwframe+0x44/0xae


stack backtrace:
CPU: 1 PID: 4250 Comm: syz-executor.3 Not tainted 5.17.0-rc2-syzkaller-00071-g1f2cfdd349b7 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106

Re: [syzbot] possible deadlock in snd_timer_interrupt (2)

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit:    38f80f42147f MAINTAINERS: Remove dead patchwork link
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=161736d6700000
kernel config:  https://syzkaller.appspot.com/x/.config?x=4e9585407e09f75f
dashboard link: https://syzkaller.appspot.com/bug?extid=1ee0910eca9c94f71f25
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=11b6ad85700000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=12527ef1700000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+1ee0910eca9c94f71f25@syzkaller.appspotmail.com

========================================================
WARNING: possible irq lock inversion dependency detected
5.17.0-rc6-syzkaller-00184-g38f80f42147f #0 Not tainted
--------------------------------------------------------
syz-executor301/4486 just changed the state of lock:
ffff88814a78a948 (&timer->lock){..-.}-{2:2}, at: snd_timer_interrupt.part.0+0x34/0xcf0 sound/core/timer.c:856
but this lock took another, SOFTIRQ-READ-unsafe lock in the past:
 (tasklist_lock){.+.+}-{2:2}


and interrupts could create inverse lock ordering between them.


other info that might help us debug this:
Chain exists of:
  &timer->lock --> &new->fa_lock --> tasklist_lock

 Possible interrupt unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(tasklist_lock);
                               local_irq_disable();
                               lock(&timer->lock);
                               lock(&new->fa_lock);
  <Interrupt>
    lock(&timer->lock);

 *** DEADLOCK ***

1 lock held by syz-executor301/4486:
 #0: ffffc90000007d70 ((&priv->tlist)){+.-.}-{0:0}, at: lockdep_copy_map include/linux/lockdep.h:35 [inline]
 #0: ffffc90000007d70 ((&priv->tlist)){+.-.}-{0:0}, at: call_timer_fn+0xd5/0x6b0 kernel/time/timer.c:1411

the shortest dependencies between 2nd lock and 1st lock:
   -> (tasklist_lock){.+.+}-{2:2} {
      HARDIRQ-ON-R at:
                          lock_acquire kernel/locking/lockdep.c:5639 [inline]
                          lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
                          __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline]
                          _raw_read_lock+0x5b/0x70 kernel/locking/spinlock.c:228
                          do_wait+0x284/0xce0 kernel/exit.c:1518
                          kernel_wait+0x9c/0x150 kernel/exit.c:1708
                          call_usermodehelper_exec_sync kernel/umh.c:139 [inline]
                          call_usermodehelper_exec_work+0xf5/0x180 kernel/umh.c:166
                          process_one_work+0x9ac/0x1650 kernel/workqueue.c:2307
                          worker_thread+0x657/0x1110 kernel/workqueue.c:2454
                          kthread+0x2e9/0x3a0 kernel/kthread.c:377
                          ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
      SOFTIRQ-ON-R at:
                          lock_acquire kernel/locking/lockdep.c:5639 [inline]
                          lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
                          __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline]
                          _raw_read_lock+0x5b/0x70 kernel/locking/spinlock.c:228
                          do_wait+0x284/0xce0 kernel/exit.c:1518
                          kernel_wait+0x9c/0x150 kernel/exit.c:1708
                          call_usermodehelper_exec_sync kernel/umh.c:139 [inline]
                          call_usermodehelper_exec_work+0xf5/0x180 kernel/umh.c:166
                          process_one_work+0x9ac/0x1650 kernel/workqueue.c:2307
                          worker_thread+0x657/0x1110 kernel/workqueue.c:2454
                          kthread+0x2e9/0x3a0 kernel/kthread.c:377
                          ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
      INITIAL USE at:
                         lock_acquire kernel/locking/lockdep.c:5639 [inline]
                         lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
                         __raw_write_lock_irq include/linux/rwlock_api_smp.h:195 [inline]
                         _raw_write_lock_irq+0x32/0x50 kernel/locking/spinlock.c:326
                         copy_process+0x486a/0x7250 kernel/fork.c:2295
                         kernel_clone+0xe7/0xab0 kernel/fork.c:2565
                         kernel_thread+0xb5/0xf0 kernel/fork.c:2617
                         rest_init+0x23/0x3e0 init/main.c:690
                         start_kernel+0x47a/0x49b init/main.c:1138
                         secondary_startup_64_no_verify+0xc3/0xcb
      INITIAL READ USE at:
                              lock_acquire kernel/locking/lockdep.c:5639 [inline]
                              lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
                              __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline]
                              _raw_read_lock+0x5b/0x70 kernel/locking/spinlock.c:228
                              do_wait+0x284/0xce0 kernel/exit.c:1518
                              kernel_wait+0x9c/0x150 kernel/exit.c:1708
                              call_usermodehelper_exec_sync kernel/umh.c:139 [inline]
                              call_usermodehelper_exec_work+0xf5/0x180 kernel/umh.c:166
                              process_one_work+0x9ac/0x1650 kernel/workqueue.c:2307
                              worker_thread+0x657/0x1110 kernel/workqueue.c:2454
                              kthread+0x2e9/0x3a0 kernel/kthread.c:377
                              ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
    }
    ... key      at: [<ffffffff8b80a098>] tasklist_lock+0x18/0x40
    ... acquired at:
   __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline]
   _raw_read_lock+0x5b/0x70 kernel/locking/spinlock.c:228
   send_sigio+0xab/0x380 fs/fcntl.c:810
   kill_fasync_rcu fs/fcntl.c:1021 [inline]
   kill_fasync fs/fcntl.c:1035 [inline]
   kill_fasync+0x1f8/0x470 fs/fcntl.c:1028
   snd_timer_user_ccallback+0x298/0x330 sound/core/timer.c:1386
   snd_timer_notify1+0x11c/0x3b0 sound/core/timer.c:516
   snd_timer_stop1+0x496/0x860 sound/core/timer.c:657
   snd_timer_stop sound/core/timer.c:710 [inline]
   snd_timer_close_locked+0x20f/0xbb0 sound/core/timer.c:408
   snd_timer_close+0x87/0xf0 sound/core/timer.c:463
   __snd_timer_user_ioctl.isra.0+0x10e2/0x2490 sound/core/timer.c:1762
   snd_timer_user_ioctl+0x77/0xb0 sound/core/timer.c:2128
   vfs_ioctl fs/ioctl.c:51 [inline]
   __do_sys_ioctl fs/ioctl.c:874 [inline]
   __se_sys_ioctl fs/ioctl.c:860 [inline]
   __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860
   do_syscall_x64 arch/x86/entry/common.c:50 [inline]
   do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
   entry_SYSCALL_64_after_hwframe+0x44/0xae

  -> (&f->f_owner.lock){....}-{2:2} {
     INITIAL USE at:
                       lock_acquire kernel/locking/lockdep.c:5639 [inline]
                       lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
                       __raw_write_lock_irq include/linux/rwlock_api_smp.h:195 [inline]
                       _raw_write_lock_irq+0x32/0x50 kernel/locking/spinlock.c:326
                       f_modown+0x2a/0x390 fs/fcntl.c:91
                       __f_setown fs/fcntl.c:110 [inline]
                       f_setown+0xd7/0x230 fs/fcntl.c:138
                       do_fcntl+0x749/0x1210 fs/fcntl.c:393
                       __do_sys_fcntl fs/fcntl.c:472 [inline]
                       __se_sys_fcntl fs/fcntl.c:457 [inline]
                       __x64_sys_fcntl+0x165/0x1e0 fs/fcntl.c:457
                       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
                       do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
                       entry_SYSCALL_64_after_hwframe+0x44/0xae
     INITIAL READ USE at:
                            lock_acquire kernel/locking/lockdep.c:5639 [inline]
                            lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
                            __raw_read_lock_irqsave include/linux/rwlock_api_smp.h:160 [inline]
                            _raw_read_lock_irqsave+0x70/0x90 kernel/locking/spinlock.c:236
                            send_sigio+0x24/0x380 fs/fcntl.c:796
                            kill_fasync_rcu fs/fcntl.c:1021 [inline]
                            kill_fasync fs/fcntl.c:1035 [inline]
                            kill_fasync+0x1f8/0x470 fs/fcntl.c:1028
                            snd_timer_user_ccallback+0x298/0x330 sound/core/timer.c:1386
                            snd_timer_notify1+0x11c/0x3b0 sound/core/timer.c:516
                            snd_timer_start1+0x4d4/0x800 sound/core/timer.c:578
                            snd_timer_start sound/core/timer.c:696 [inline]
                            snd_timer_start sound/core/timer.c:689 [inline]
                            snd_timer_user_start.isra.0+0x1e3/0x260 sound/core/timer.c:1984
                            __snd_timer_user_ioctl.isra.0+0xda8/0x2490 sound/core/timer.c:2107
                            snd_timer_user_ioctl+0x77/0xb0 sound/core/timer.c:2128
                            vfs_ioctl fs/ioctl.c:51 [inline]
                            __do_sys_ioctl fs/ioctl.c:874 [inline]
                            __se_sys_ioctl fs/ioctl.c:860 [inline]
                            __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860
                            do_syscall_x64 arch/x86/entry/common.c:50 [inline]
                            do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
                            entry_SYSCALL_64_after_hwframe+0x44/0xae
   }
   ... key      at: [<ffffffff90585a40>] __key.5+0x0/0x40
   ... acquired at:
   __raw_read_lock_irqsave include/linux/rwlock_api_smp.h:160 [inline]
   _raw_read_lock_irqsave+0x70/0x90 kernel/locking/spinlock.c:236
   send_sigio+0x24/0x380 fs/fcntl.c:796
   kill_fasync_rcu fs/fcntl.c:1021 [inline]
   kill_fasync fs/fcntl.c:1035 [inline]
   kill_fasync+0x1f8/0x470 fs/fcntl.c:1028
   snd_timer_user_ccallback+0x298/0x330 sound/core/timer.c:1386
   snd_timer_notify1+0x11c/0x3b0 sound/core/timer.c:516
   snd_timer_start1+0x4d4/0x800 sound/core/timer.c:578
   snd_timer_start sound/core/timer.c:696 [inline]
   snd_timer_start sound/core/timer.c:689 [inline]
   snd_timer_user_start.isra.0+0x1e3/0x260 sound/core/timer.c:1984
   __snd_timer_user_ioctl.isra.0+0xda8/0x2490 sound/core/timer.c:2107
   snd_timer_user_ioctl+0x77/0xb0 sound/core/timer.c:2128
   vfs_ioctl fs/ioctl.c:51 [inline]
   __do_sys_ioctl fs/ioctl.c:874 [inline]
   __se_sys_ioctl fs/ioctl.c:860 [inline]
   __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860
   do_syscall_x64 arch/x86/entry/common.c:50 [inline]
   do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
   entry_SYSCALL_64_after_hwframe+0x44/0xae

 -> (&new->fa_lock){....}-{2:2} {
    INITIAL USE at:
                     lock_acquire kernel/locking/lockdep.c:5639 [inline]
                     lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
                     __raw_write_lock_irq include/linux/rwlock_api_smp.h:195 [inline]
                     _raw_write_lock_irq+0x32/0x50 kernel/locking/spinlock.c:326
                     fasync_remove_entry+0xb6/0x1f0 fs/fcntl.c:891
                     fasync_helper+0x9e/0xb0 fs/fcntl.c:994
                     __fput+0x846/0x9f0 fs/file_table.c:314
                     task_work_run+0xdd/0x1a0 kernel/task_work.c:164
                     exit_task_work include/linux/task_work.h:32 [inline]
                     do_exit+0xb29/0x2a30 kernel/exit.c:806
                     do_group_exit+0xd2/0x2f0 kernel/exit.c:935
                     __do_sys_exit_group kernel/exit.c:946 [inline]
                     __se_sys_exit_group kernel/exit.c:944 [inline]
                     __x64_sys_exit_group+0x3a/0x50 kernel/exit.c:944
                     do_syscall_x64 arch/x86/entry/common.c:50 [inline]
                     do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
                     entry_SYSCALL_64_after_hwframe+0x44/0xae
    INITIAL READ USE at:
                          lock_acquire kernel/locking/lockdep.c:5639 [inline]
                          lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
                          __raw_read_lock_irqsave include/linux/rwlock_api_smp.h:160 [inline]
                          _raw_read_lock_irqsave+0x70/0x90 kernel/locking/spinlock.c:236
                          kill_fasync_rcu fs/fcntl.c:1014 [inline]
                          kill_fasync fs/fcntl.c:1035 [inline]
                          kill_fasync+0x136/0x470 fs/fcntl.c:1028
                          snd_timer_user_ccallback+0x298/0x330 sound/core/timer.c:1386
                          snd_timer_notify1+0x11c/0x3b0 sound/core/timer.c:516
                          snd_timer_start1+0x4d4/0x800 sound/core/timer.c:578
                          snd_timer_start sound/core/timer.c:696 [inline]
                          snd_timer_start sound/core/timer.c:689 [inline]
                          snd_timer_user_start.isra.0+0x1e3/0x260 sound/core/timer.c:1984
                          __snd_timer_user_ioctl.isra.0+0xda8/0x2490 sound/core/timer.c:2107
                          snd_timer_user_ioctl+0x77/0xb0 sound/core/timer.c:2128
                          vfs_ioctl fs/ioctl.c:51 [inline]
                          __do_sys_ioctl fs/ioctl.c:874 [inline]
                          __se_sys_ioctl fs/ioctl.c:860 [inline]
                          __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860
                          do_syscall_x64 arch/x86/entry/common.c:50 [inline]
                          do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
                          entry_SYSCALL_64_after_hwframe+0x44/0xae
  }
  ... key      at: [<ffffffff90586820>] __key.0+0x0/0x40
  ... acquired at:
   __raw_read_lock_irqsave include/linux/rwlock_api_smp.h:160 [inline]
   _raw_read_lock_irqsave+0x70/0x90 kernel/locking/spinlock.c:236
   kill_fasync_rcu fs/fcntl.c:1014 [inline]
   kill_fasync fs/fcntl.c:1035 [inline]
   kill_fasync+0x136/0x470 fs/fcntl.c:1028
   snd_timer_user_ccallback+0x298/0x330 sound/core/timer.c:1386
   snd_timer_notify1+0x11c/0x3b0 sound/core/timer.c:516
   snd_timer_start1+0x4d4/0x800 sound/core/timer.c:578
   snd_timer_start sound/core/timer.c:696 [inline]
   snd_timer_start sound/core/timer.c:689 [inline]
   snd_timer_user_start.isra.0+0x1e3/0x260 sound/core/timer.c:1984
   __snd_timer_user_ioctl.isra.0+0xda8/0x2490 sound/core/timer.c:2107
   snd_timer_user_ioctl+0x77/0xb0 sound/core/timer.c:2128
   vfs_ioctl fs/ioctl.c:51 [inline]
   __do_sys_ioctl fs/ioctl.c:874 [inline]
   __se_sys_ioctl fs/ioctl.c:860 [inline]
   __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860
   do_syscall_x64 arch/x86/entry/common.c:50 [inline]
   do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
   entry_SYSCALL_64_after_hwframe+0x44/0xae

-> (&timer->lock){..-.}-{2:2} {
   IN-SOFTIRQ-W at:
                    lock_acquire kernel/locking/lockdep.c:5639 [inline]
                    lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
                    __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
                    _raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:162
                    snd_timer_interrupt.part.0+0x34/0xcf0 sound/core/timer.c:856
                    snd_timer_interrupt sound/core/timer.c:1154 [inline]
                    snd_timer_s_function+0x14b/0x200 sound/core/timer.c:1154
                    call_timer_fn+0x1a5/0x6b0 kernel/time/timer.c:1421
                    expire_timers kernel/time/timer.c:1466 [inline]
                    __run_timers.part.0+0x67c/0xa30 kernel/time/timer.c:1734
                    __run_timers kernel/time/timer.c:1715 [inline]
                    run_timer_softirq+0xb3/0x1d0 kernel/time/timer.c:1747
                    __do_softirq+0x29b/0x9c2 kernel/softirq.c:558
                    invoke_softirq kernel/softirq.c:432 [inline]
                    __irq_exit_rcu+0x123/0x180 kernel/softirq.c:637
                    irq_exit_rcu+0x5/0x20 kernel/softirq.c:649
                    sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1097
                    asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638
                    bytes_is_nonzero mm/kasan/generic.c:85 [inline]
                    memory_is_nonzero mm/kasan/generic.c:102 [inline]
                    memory_is_poisoned_n mm/kasan/generic.c:128 [inline]
                    memory_is_poisoned mm/kasan/generic.c:159 [inline]
                    check_region_inline mm/kasan/generic.c:180 [inline]
                    kasan_check_range+0xde/0x180 mm/kasan/generic.c:189
                    instrument_atomic_read include/linux/instrumented.h:71 [inline]
                    atomic_long_read include/linux/atomic/atomic-instrumented.h:1265 [inline]
                    filp_close+0x22/0x170 fs/open.c:1318
                    close_files fs/file.c:403 [inline]
                    put_files_struct fs/file.c:418 [inline]
                    put_files_struct+0x1d0/0x350 fs/file.c:415
                    exit_files+0x7e/0xa0 fs/file.c:435
                    do_exit+0xaf2/0x2a30 kernel/exit.c:801
                    do_group_exit+0xd2/0x2f0 kernel/exit.c:935
                    __do_sys_exit_group kernel/exit.c:946 [inline]
                    __se_sys_exit_group kernel/exit.c:944 [inline]
                    __x64_sys_exit_group+0x3a/0x50 kernel/exit.c:944
                    do_syscall_x64 arch/x86/entry/common.c:50 [inline]
                    do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
                    entry_SYSCALL_64_after_hwframe+0x44/0xae
   INITIAL USE at:
                   lock_acquire kernel/locking/lockdep.c:5639 [inline]
                   lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
                   __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
                   _raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:162
                   snd_timer_stop1+0x5c/0x860 sound/core/timer.c:626
                   snd_timer_stop sound/core/timer.c:710 [inline]
                   snd_timer_user_start.isra.0+0x8b/0x260 sound/core/timer.c:1981
                   __snd_timer_user_ioctl.isra.0+0xda8/0x2490 sound/core/timer.c:2107
                   snd_timer_user_ioctl+0x77/0xb0 sound/core/timer.c:2128
                   vfs_ioctl fs/ioctl.c:51 [inline]
                   __do_sys_ioctl fs/ioctl.c:874 [inline]
                   __se_sys_ioctl fs/ioctl.c:860 [inline]
                   __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860
                   do_syscall_x64 arch/x86/entry/common.c:50 [inline]
                   do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
                   entry_SYSCALL_64_after_hwframe+0x44/0xae
 }
 ... key      at: [<ffffffff908843c0>] __key.12+0x0/0x40
 ... acquired at:
   mark_lock kernel/locking/lockdep.c:4569 [inline]
   mark_usage kernel/locking/lockdep.c:4500 [inline]
   __lock_acquire+0x11e3/0x56c0 kernel/locking/lockdep.c:4981
   lock_acquire kernel/locking/lockdep.c:5639 [inline]
   lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
   __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
   _raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:162
   snd_timer_interrupt.part.0+0x34/0xcf0 sound/core/timer.c:856
   snd_timer_interrupt sound/core/timer.c:1154 [inline]
   snd_timer_s_function+0x14b/0x200 sound/core/timer.c:1154
   call_timer_fn+0x1a5/0x6b0 kernel/time/timer.c:1421
   expire_timers kernel/time/timer.c:1466 [inline]
   __run_timers.part.0+0x67c/0xa30 kernel/time/timer.c:1734
   __run_timers kernel/time/timer.c:1715 [inline]
   run_timer_softirq+0xb3/0x1d0 kernel/time/timer.c:1747
   __do_softirq+0x29b/0x9c2 kernel/softirq.c:558
   invoke_softirq kernel/softirq.c:432 [inline]
   __irq_exit_rcu+0x123/0x180 kernel/softirq.c:637
   irq_exit_rcu+0x5/0x20 kernel/softirq.c:649
   sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1097
   asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638
   bytes_is_nonzero mm/kasan/generic.c:85 [inline]
   memory_is_nonzero mm/kasan/generic.c:102 [inline]
   memory_is_poisoned_n mm/kasan/generic.c:128 [inline]
   memory_is_poisoned mm/kasan/generic.c:159 [inline]
   check_region_inline mm/kasan/generic.c:180 [inline]
   kasan_check_range+0xde/0x180 mm/kasan/generic.c:189
   instrument_atomic_read include/linux/instrumented.h:71 [inline]
   atomic_long_read include/linux/atomic/atomic-instrumented.h:1265 [inline]
   filp_close+0x22/0x170 fs/open.c:1318
   close_files fs/file.c:403 [inline]
   put_files_struct fs/file.c:418 [inline]
   put_files_struct+0x1d0/0x350 fs/file.c:415
   exit_files+0x7e/0xa0 fs/file.c:435
   do_exit+0xaf2/0x2a30 kernel/exit.c:801
   do_group_exit+0xd2/0x2f0 kernel/exit.c:935
   __do_sys_exit_group kernel/exit.c:946 [inline]
   __se_sys_exit_group kernel/exit.c:944 [inline]
   __x64_sys_exit_group+0x3a/0x50 kernel/exit.c:944
   do_syscall_x64 arch/x86/entry/common.c:50 [inline]
   do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
   entry_SYSCALL_64_after_hwframe+0x44/0xae


stack backtrace:
CPU: 0 PID: 4486 Comm: syz-executor301 Not tainted 5.17.0-rc6-syzkaller-00184-g38f80f42147f #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
 print_irq_inversion_bug kernel/locking/lockdep.c:194 [inline]
 check_usage_forwards kernel/locking/lockdep.c:4043 [inline]
 mark_lock_irq kernel/locking/lockdep.c:4175 [inline]
 mark_lock.part.0.cold+0x86/0xd8 kernel/locking/lockdep.c:4605
 mark_lock kernel/locking/lockdep.c:4569 [inline]
 mark_usage kernel/locking/lockdep.c:4500 [inline]
 __lock_acquire+0x11e3/0x56c0 kernel/locking/lockdep.c:4981
 lock_acquire kernel/locking/lockdep.c:5639 [inline]
 lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:162
 snd_timer_interrupt.part.0+0x34/0xcf0 sound/core/timer.c:856
 snd_timer_interrupt sound/core/timer.c:1154 [inline]
 snd_timer_s_function+0x14b/0x200 sound/core/timer.c:1154
 call_timer_fn+0x1a5/0x6b0 kernel/time/timer.c:1421
 expire_timers kernel/time/timer.c:1466 [inline]
 __run_timers.part.0+0x67c/0xa30 kernel/time/timer.c:1734
 __run_timers kernel/time/timer.c:1715 [inline]
 run_timer_softirq+0xb3/0x1d0 kernel/time/timer.c:1747
 __do_softirq+0x29b/0x9c2 kernel/softirq.c:558
 invoke_softirq kernel/softirq.c:432 [inline]
 __irq_exit_rcu+0x123/0x180 kernel/softirq.c:637
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:649
 sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1097
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638
RIP: 0010:bytes_is_nonzero mm/kasan/generic.c:85 [inline]
RIP: 0010:memory_is_nonzero mm/kasan/generic.c:102 [inline]
RIP: 0010:memory_is_poisoned_n mm/kasan/generic.c:128 [inline]
RIP: 0010:memory_is_poisoned mm/kasan/generic.c:159 [inline]
RIP: 0010:check_region_inline mm/kasan/generic.c:180 [inline]
RIP: 0010:kasan_check_range+0xde/0x180 mm/kasan/generic.c:189
Code: 74 f2 48 89 c2 b8 01 00 00 00 48 85 d2 75 56 5b 5d 41 5c c3 48 85 d2 74 5e 48 01 ea eb 09 48 83 c0 01 48 39 d0 74 50 80 38 00 <74> f2 eb d4 41 bc 08 00 00 00 48 89 ea 45 29 dc 4d 8d 1c 2c eb 0c
RSP: 0018:ffffc9000376fd30 EFLAGS: 00000246
RAX: ffffed100f1d3d9f RBX: ffffed100f1d3da0 RCX: ffffffff81cb24b2
RDX: ffffed100f1d3da0 RSI: 0000000000000008 RDI: ffff888078e9ecf8
RBP: ffffed100f1d3d9f R08: 0000000000000000 R09: ffff888078e9ecff
R10: ffffed100f1d3d9f R11: 0000000000000000 R12: ffff88807ee70f00
R13: ffff888078e9ecf8 R14: ffff88807ee70f00 R15: ffff88807ee71028
 instrument_atomic_read include/linux/instrumented.h:71 [inline]
 atomic_long_read include/linux/atomic/atomic-instrumented.h:1265 [inline]
 filp_close+0x22/0x170 fs/open.c:1318
 close_files fs/file.c:403 [inline]
 put_files_struct fs/file.c:418 [inline]
 put_files_struct+0x1d0/0x350 fs/file.c:415
 exit_files+0x7e/0xa0 fs/file.c:435
 do_exit+0xaf2/0x2a30 kernel/exit.c:801
 do_group_exit+0xd2/0x2f0 kernel/exit.c:935
 __do_sys_exit_group kernel/exit.c:946 [inline]
 __se_sys_exit_group kernel/exit.c:944 [inline]
 __x64_sys_exit_group+0x3a/0x50 kernel/exit.c:944
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7ff95f986c99
Code: Unable to access opcode bytes at RIP 0x7ff95f986c6f.
RSP: 002b:00007ffecd4a5e98 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 00007ff95f9fb330 RCX: 00007ff95f986c99
RDX: 000000000000003c RSI: 00000000000000e7 RDI: 0000000000000000
RBP: 0000000000000000 R08: ffffffffffffffc0 R09: 0000000000000001
R10: 0000000000000001 R11: 0000000000000246 R12: 00007ff95f9fb330
R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000001
 </TASK>
----------------
Code disassembly (best guess):
   0:	74 f2                	je     0xfffffff4
   2:	48 89 c2             	mov    %rax,%rdx
   5:	b8 01 00 00 00       	mov    $0x1,%eax
   a:	48 85 d2             	test   %rdx,%rdx
   d:	75 56                	jne    0x65
   f:	5b                   	pop    %rbx
  10:	5d                   	pop    %rbp
  11:	41 5c                	pop    %r12
  13:	c3                   	retq
  14:	48 85 d2             	test   %rdx,%rdx
  17:	74 5e                	je     0x77
  19:	48 01 ea             	add    %rbp,%rdx
  1c:	eb 09                	jmp    0x27
  1e:	48 83 c0 01          	add    $0x1,%rax
  22:	48 39 d0             	cmp    %rdx,%rax
  25:	74 50                	je     0x77
  27:	80 38 00             	cmpb   $0x0,(%rax)
* 2a:	74 f2                	je     0x1e <-- trapping instruction
  2c:	eb d4                	jmp    0x2
  2e:	41 bc 08 00 00 00    	mov    $0x8,%r12d
  34:	48 89 ea             	mov    %rbp,%rdx
  37:	45 29 dc             	sub    %r11d,%r12d
  3a:	4d 8d 1c 2c          	lea    (%r12,%rbp,1),%r11
  3e:	eb 0c                	jmp    0x4c

Re: [syzbot] possible deadlock in snd_timer_interrupt (2)

[Hillf Danton]

On Fri, 04 Mar 2022 06:46:26 -0800
> syzbot has found a reproducer for the following issue on:
> 
> HEAD commit:    38f80f42147f MAINTAINERS: Remove dead patchwork link
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=161736d6700000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=4e9585407e09f75f
> dashboard link: https://syzkaller.appspot.com/bug?extid=1ee0910eca9c94f71f25
> compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=11b6ad85700000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=12527ef1700000
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+1ee0910eca9c94f71f25@syzkaller.appspotmail.com
> 
> ========================================================
> WARNING: possible irq lock inversion dependency detected
> 5.17.0-rc6-syzkaller-00184-g38f80f42147f #0 Not tainted
> --------------------------------------------------------
> syz-executor301/4486 just changed the state of lock:
> ffff88814a78a948 (&timer->lock){..-.}-{2:2}, at: snd_timer_interrupt.part.0+0x34/0xcf0 sound/core/timer.c:856
> but this lock took another, SOFTIRQ-READ-unsafe lock in the past:
>  (tasklist_lock){.+.+}-{2:2}
> 
> 
> and interrupts could create inverse lock ordering between them.
> 
> 
> other info that might help us debug this:
> Chain exists of:
>   &timer->lock --> &new->fa_lock --> tasklist_lock
> 
>  Possible interrupt unsafe locking scenario:
> 
>        CPU0                    CPU1
>        ----                    ----
>   lock(tasklist_lock);
>                                local_irq_disable();
>                                lock(&timer->lock);
>                                lock(&new->fa_lock);
>   <Interrupt>
>     lock(&timer->lock);
> 
>  *** DEADLOCK ***
> 
> 1 lock held by syz-executor301/4486:
>  #0: ffffc90000007d70 ((&priv->tlist)){+.-.}-{0:0}, at: lockdep_copy_map include/linux/lockdep.h:35 [inline]
>  #0: ffffc90000007d70 ((&priv->tlist)){+.-.}-{0:0}, at: call_timer_fn+0xd5/0x6b0 kernel/time/timer.c:1411
> 
> the shortest dependencies between 2nd lock and 1st lock:
>    -> (tasklist_lock){.+.+}-{2:2} {
>       HARDIRQ-ON-R at:
>                           lock_acquire kernel/locking/lockdep.c:5639 [inline]
>                           lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
>                           __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline]
>                           _raw_read_lock+0x5b/0x70 kernel/locking/spinlock.c:228
>                           do_wait+0x284/0xce0 kernel/exit.c:1518
>                           kernel_wait+0x9c/0x150 kernel/exit.c:1708
>                           call_usermodehelper_exec_sync kernel/umh.c:139 [inline]
>                           call_usermodehelper_exec_work+0xf5/0x180 kernel/umh.c:166
>                           process_one_work+0x9ac/0x1650 kernel/workqueue.c:2307
>                           worker_thread+0x657/0x1110 kernel/workqueue.c:2454
>                           kthread+0x2e9/0x3a0 kernel/kthread.c:377
>                           ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
>       SOFTIRQ-ON-R at:
>                           lock_acquire kernel/locking/lockdep.c:5639 [inline]
>                           lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
>                           __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline]
>                           _raw_read_lock+0x5b/0x70 kernel/locking/spinlock.c:228
>                           do_wait+0x284/0xce0 kernel/exit.c:1518
>                           kernel_wait+0x9c/0x150 kernel/exit.c:1708
>                           call_usermodehelper_exec_sync kernel/umh.c:139 [inline]
>                           call_usermodehelper_exec_work+0xf5/0x180 kernel/umh.c:166
>                           process_one_work+0x9ac/0x1650 kernel/workqueue.c:2307
>                           worker_thread+0x657/0x1110 kernel/workqueue.c:2454
>                           kthread+0x2e9/0x3a0 kernel/kthread.c:377
>                           ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
>       INITIAL USE at:
>                          lock_acquire kernel/locking/lockdep.c:5639 [inline]
>                          lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
>                          __raw_write_lock_irq include/linux/rwlock_api_smp.h:195 [inline]
>                          _raw_write_lock_irq+0x32/0x50 kernel/locking/spinlock.c:326
>                          copy_process+0x486a/0x7250 kernel/fork.c:2295
>                          kernel_clone+0xe7/0xab0 kernel/fork.c:2565
>                          kernel_thread+0xb5/0xf0 kernel/fork.c:2617
>                          rest_init+0x23/0x3e0 init/main.c:690
>                          start_kernel+0x47a/0x49b init/main.c:1138
>                          secondary_startup_64_no_verify+0xc3/0xcb
>       INITIAL READ USE at:
>                               lock_acquire kernel/locking/lockdep.c:5639 [inline]
>                               lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
>                               __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline]
>                               _raw_read_lock+0x5b/0x70 kernel/locking/spinlock.c:228
>                               do_wait+0x284/0xce0 kernel/exit.c:1518
>                               kernel_wait+0x9c/0x150 kernel/exit.c:1708
>                               call_usermodehelper_exec_sync kernel/umh.c:139 [inline]
>                               call_usermodehelper_exec_work+0xf5/0x180 kernel/umh.c:166
>                               process_one_work+0x9ac/0x1650 kernel/workqueue.c:2307
>                               worker_thread+0x657/0x1110 kernel/workqueue.c:2454
>                               kthread+0x2e9/0x3a0 kernel/kthread.c:377
>                               ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
>     }
>     ... key      at: [<ffffffff8b80a098>] tasklist_lock+0x18/0x40
>     ... acquired at:
>    __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline]
>    _raw_read_lock+0x5b/0x70 kernel/locking/spinlock.c:228
>    send_sigio+0xab/0x380 fs/fcntl.c:810
>    kill_fasync_rcu fs/fcntl.c:1021 [inline]
>    kill_fasync fs/fcntl.c:1035 [inline]
>    kill_fasync+0x1f8/0x470 fs/fcntl.c:1028
>    snd_timer_user_ccallback+0x298/0x330 sound/core/timer.c:1386
>    snd_timer_notify1+0x11c/0x3b0 sound/core/timer.c:516
>    snd_timer_stop1+0x496/0x860 sound/core/timer.c:657
>    snd_timer_stop sound/core/timer.c:710 [inline]
>    snd_timer_close_locked+0x20f/0xbb0 sound/core/timer.c:408
>    snd_timer_close+0x87/0xf0 sound/core/timer.c:463
>    __snd_timer_user_ioctl.isra.0+0x10e2/0x2490 sound/core/timer.c:1762
>    snd_timer_user_ioctl+0x77/0xb0 sound/core/timer.c:2128
>    vfs_ioctl fs/ioctl.c:51 [inline]
>    __do_sys_ioctl fs/ioctl.c:874 [inline]
>    __se_sys_ioctl fs/ioctl.c:860 [inline]
>    __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860
>    do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>    do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
>    entry_SYSCALL_64_after_hwframe+0x44/0xae
> 
>   -> (&f->f_owner.lock){....}-{2:2} {
>      INITIAL USE at:
>                        lock_acquire kernel/locking/lockdep.c:5639 [inline]
>                        lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
>                        __raw_write_lock_irq include/linux/rwlock_api_smp.h:195 [inline]
>                        _raw_write_lock_irq+0x32/0x50 kernel/locking/spinlock.c:326
>                        f_modown+0x2a/0x390 fs/fcntl.c:91
>                        __f_setown fs/fcntl.c:110 [inline]
>                        f_setown+0xd7/0x230 fs/fcntl.c:138
>                        do_fcntl+0x749/0x1210 fs/fcntl.c:393
>                        __do_sys_fcntl fs/fcntl.c:472 [inline]
>                        __se_sys_fcntl fs/fcntl.c:457 [inline]
>                        __x64_sys_fcntl+0x165/0x1e0 fs/fcntl.c:457
>                        do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>                        do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
>                        entry_SYSCALL_64_after_hwframe+0x44/0xae
>      INITIAL READ USE at:
>                             lock_acquire kernel/locking/lockdep.c:5639 [inline]
>                             lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
>                             __raw_read_lock_irqsave include/linux/rwlock_api_smp.h:160 [inline]
>                             _raw_read_lock_irqsave+0x70/0x90 kernel/locking/spinlock.c:236
>                             send_sigio+0x24/0x380 fs/fcntl.c:796
>                             kill_fasync_rcu fs/fcntl.c:1021 [inline]
>                             kill_fasync fs/fcntl.c:1035 [inline]
>                             kill_fasync+0x1f8/0x470 fs/fcntl.c:1028
>                             snd_timer_user_ccallback+0x298/0x330 sound/core/timer.c:1386
>                             snd_timer_notify1+0x11c/0x3b0 sound/core/timer.c:516
>                             snd_timer_start1+0x4d4/0x800 sound/core/timer.c:578
>                             snd_timer_start sound/core/timer.c:696 [inline]
>                             snd_timer_start sound/core/timer.c:689 [inline]
>                             snd_timer_user_start.isra.0+0x1e3/0x260 sound/core/timer.c:1984
>                             __snd_timer_user_ioctl.isra.0+0xda8/0x2490 sound/core/timer.c:2107
>                             snd_timer_user_ioctl+0x77/0xb0 sound/core/timer.c:2128
>                             vfs_ioctl fs/ioctl.c:51 [inline]
>                             __do_sys_ioctl fs/ioctl.c:874 [inline]
>                             __se_sys_ioctl fs/ioctl.c:860 [inline]
>                             __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860
>                             do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>                             do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
>                             entry_SYSCALL_64_after_hwframe+0x44/0xae
>    }
>    ... key      at: [<ffffffff90585a40>] __key.5+0x0/0x40
>    ... acquired at:
>    __raw_read_lock_irqsave include/linux/rwlock_api_smp.h:160 [inline]
>    _raw_read_lock_irqsave+0x70/0x90 kernel/locking/spinlock.c:236
>    send_sigio+0x24/0x380 fs/fcntl.c:796
>    kill_fasync_rcu fs/fcntl.c:1021 [inline]
>    kill_fasync fs/fcntl.c:1035 [inline]
>    kill_fasync+0x1f8/0x470 fs/fcntl.c:1028
>    snd_timer_user_ccallback+0x298/0x330 sound/core/timer.c:1386
>    snd_timer_notify1+0x11c/0x3b0 sound/core/timer.c:516
>    snd_timer_start1+0x4d4/0x800 sound/core/timer.c:578
>    snd_timer_start sound/core/timer.c:696 [inline]
>    snd_timer_start sound/core/timer.c:689 [inline]
>    snd_timer_user_start.isra.0+0x1e3/0x260 sound/core/timer.c:1984
>    __snd_timer_user_ioctl.isra.0+0xda8/0x2490 sound/core/timer.c:2107
>    snd_timer_user_ioctl+0x77/0xb0 sound/core/timer.c:2128
>    vfs_ioctl fs/ioctl.c:51 [inline]
>    __do_sys_ioctl fs/ioctl.c:874 [inline]
>    __se_sys_ioctl fs/ioctl.c:860 [inline]
>    __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860
>    do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>    do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
>    entry_SYSCALL_64_after_hwframe+0x44/0xae
> 
>  -> (&new->fa_lock){....}-{2:2} {
>     INITIAL USE at:
>                      lock_acquire kernel/locking/lockdep.c:5639 [inline]
>                      lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
>                      __raw_write_lock_irq include/linux/rwlock_api_smp.h:195 [inline]
>                      _raw_write_lock_irq+0x32/0x50 kernel/locking/spinlock.c:326
>                      fasync_remove_entry+0xb6/0x1f0 fs/fcntl.c:891
>                      fasync_helper+0x9e/0xb0 fs/fcntl.c:994
>                      __fput+0x846/0x9f0 fs/file_table.c:314
>                      task_work_run+0xdd/0x1a0 kernel/task_work.c:164
>                      exit_task_work include/linux/task_work.h:32 [inline]
>                      do_exit+0xb29/0x2a30 kernel/exit.c:806
>                      do_group_exit+0xd2/0x2f0 kernel/exit.c:935
>                      __do_sys_exit_group kernel/exit.c:946 [inline]
>                      __se_sys_exit_group kernel/exit.c:944 [inline]
>                      __x64_sys_exit_group+0x3a/0x50 kernel/exit.c:944
>                      do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>                      do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
>                      entry_SYSCALL_64_after_hwframe+0x44/0xae
>     INITIAL READ USE at:
>                           lock_acquire kernel/locking/lockdep.c:5639 [inline]
>                           lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
>                           __raw_read_lock_irqsave include/linux/rwlock_api_smp.h:160 [inline]
>                           _raw_read_lock_irqsave+0x70/0x90 kernel/locking/spinlock.c:236
>                           kill_fasync_rcu fs/fcntl.c:1014 [inline]
>                           kill_fasync fs/fcntl.c:1035 [inline]
>                           kill_fasync+0x136/0x470 fs/fcntl.c:1028
>                           snd_timer_user_ccallback+0x298/0x330 sound/core/timer.c:1386
>                           snd_timer_notify1+0x11c/0x3b0 sound/core/timer.c:516
>                           snd_timer_start1+0x4d4/0x800 sound/core/timer.c:578
>                           snd_timer_start sound/core/timer.c:696 [inline]
>                           snd_timer_start sound/core/timer.c:689 [inline]
>                           snd_timer_user_start.isra.0+0x1e3/0x260 sound/core/timer.c:1984
>                           __snd_timer_user_ioctl.isra.0+0xda8/0x2490 sound/core/timer.c:2107
>                           snd_timer_user_ioctl+0x77/0xb0 sound/core/timer.c:2128
>                           vfs_ioctl fs/ioctl.c:51 [inline]
>                           __do_sys_ioctl fs/ioctl.c:874 [inline]
>                           __se_sys_ioctl fs/ioctl.c:860 [inline]
>                           __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860
>                           do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>                           do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
>                           entry_SYSCALL_64_after_hwframe+0x44/0xae
>   }
>   ... key      at: [<ffffffff90586820>] __key.0+0x0/0x40
>   ... acquired at:
>    __raw_read_lock_irqsave include/linux/rwlock_api_smp.h:160 [inline]
>    _raw_read_lock_irqsave+0x70/0x90 kernel/locking/spinlock.c:236
>    kill_fasync_rcu fs/fcntl.c:1014 [inline]
>    kill_fasync fs/fcntl.c:1035 [inline]
>    kill_fasync+0x136/0x470 fs/fcntl.c:1028
>    snd_timer_user_ccallback+0x298/0x330 sound/core/timer.c:1386
>    snd_timer_notify1+0x11c/0x3b0 sound/core/timer.c:516
>    snd_timer_start1+0x4d4/0x800 sound/core/timer.c:578
>    snd_timer_start sound/core/timer.c:696 [inline]
>    snd_timer_start sound/core/timer.c:689 [inline]
>    snd_timer_user_start.isra.0+0x1e3/0x260 sound/core/timer.c:1984
>    __snd_timer_user_ioctl.isra.0+0xda8/0x2490 sound/core/timer.c:2107
>    snd_timer_user_ioctl+0x77/0xb0 sound/core/timer.c:2128
>    vfs_ioctl fs/ioctl.c:51 [inline]
>    __do_sys_ioctl fs/ioctl.c:874 [inline]
>    __se_sys_ioctl fs/ioctl.c:860 [inline]
>    __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860
>    do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>    do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
>    entry_SYSCALL_64_after_hwframe+0x44/0xae
> 
> -> (&timer->lock){..-.}-{2:2} {
>    IN-SOFTIRQ-W at:
>                     lock_acquire kernel/locking/lockdep.c:5639 [inline]
>                     lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
>                     __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
>                     _raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:162
>                     snd_timer_interrupt.part.0+0x34/0xcf0 sound/core/timer.c:856
>                     snd_timer_interrupt sound/core/timer.c:1154 [inline]
>                     snd_timer_s_function+0x14b/0x200 sound/core/timer.c:1154
>                     call_timer_fn+0x1a5/0x6b0 kernel/time/timer.c:1421
>                     expire_timers kernel/time/timer.c:1466 [inline]
>                     __run_timers.part.0+0x67c/0xa30 kernel/time/timer.c:1734
>                     __run_timers kernel/time/timer.c:1715 [inline]
>                     run_timer_softirq+0xb3/0x1d0 kernel/time/timer.c:1747
>                     __do_softirq+0x29b/0x9c2 kernel/softirq.c:558
>                     invoke_softirq kernel/softirq.c:432 [inline]
>                     __irq_exit_rcu+0x123/0x180 kernel/softirq.c:637
>                     irq_exit_rcu+0x5/0x20 kernel/softirq.c:649
>                     sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1097
>                     asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638
>                     bytes_is_nonzero mm/kasan/generic.c:85 [inline]
>                     memory_is_nonzero mm/kasan/generic.c:102 [inline]
>                     memory_is_poisoned_n mm/kasan/generic.c:128 [inline]
>                     memory_is_poisoned mm/kasan/generic.c:159 [inline]
>                     check_region_inline mm/kasan/generic.c:180 [inline]
>                     kasan_check_range+0xde/0x180 mm/kasan/generic.c:189
>                     instrument_atomic_read include/linux/instrumented.h:71 [inline]
>                     atomic_long_read include/linux/atomic/atomic-instrumented.h:1265 [inline]
>                     filp_close+0x22/0x170 fs/open.c:1318
>                     close_files fs/file.c:403 [inline]
>                     put_files_struct fs/file.c:418 [inline]
>                     put_files_struct+0x1d0/0x350 fs/file.c:415
>                     exit_files+0x7e/0xa0 fs/file.c:435
>                     do_exit+0xaf2/0x2a30 kernel/exit.c:801
>                     do_group_exit+0xd2/0x2f0 kernel/exit.c:935
>                     __do_sys_exit_group kernel/exit.c:946 [inline]
>                     __se_sys_exit_group kernel/exit.c:944 [inline]
>                     __x64_sys_exit_group+0x3a/0x50 kernel/exit.c:944
>                     do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>                     do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
>                     entry_SYSCALL_64_after_hwframe+0x44/0xae
>    INITIAL USE at:
>                    lock_acquire kernel/locking/lockdep.c:5639 [inline]
>                    lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
>                    __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
>                    _raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:162
>                    snd_timer_stop1+0x5c/0x860 sound/core/timer.c:626
>                    snd_timer_stop sound/core/timer.c:710 [inline]
>                    snd_timer_user_start.isra.0+0x8b/0x260 sound/core/timer.c:1981
>                    __snd_timer_user_ioctl.isra.0+0xda8/0x2490 sound/core/timer.c:2107
>                    snd_timer_user_ioctl+0x77/0xb0 sound/core/timer.c:2128
>                    vfs_ioctl fs/ioctl.c:51 [inline]
>                    __do_sys_ioctl fs/ioctl.c:874 [inline]
>                    __se_sys_ioctl fs/ioctl.c:860 [inline]
>                    __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860
>                    do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>                    do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
>                    entry_SYSCALL_64_after_hwframe+0x44/0xae
>  }
>  ... key      at: [<ffffffff908843c0>] __key.12+0x0/0x40
>  ... acquired at:
>    mark_lock kernel/locking/lockdep.c:4569 [inline]
>    mark_usage kernel/locking/lockdep.c:4500 [inline]
>    __lock_acquire+0x11e3/0x56c0 kernel/locking/lockdep.c:4981
>    lock_acquire kernel/locking/lockdep.c:5639 [inline]
>    lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
>    __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
>    _raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:162
>    snd_timer_interrupt.part.0+0x34/0xcf0 sound/core/timer.c:856
>    snd_timer_interrupt sound/core/timer.c:1154 [inline]
>    snd_timer_s_function+0x14b/0x200 sound/core/timer.c:1154
>    call_timer_fn+0x1a5/0x6b0 kernel/time/timer.c:1421
>    expire_timers kernel/time/timer.c:1466 [inline]
>    __run_timers.part.0+0x67c/0xa30 kernel/time/timer.c:1734
>    __run_timers kernel/time/timer.c:1715 [inline]
>    run_timer_softirq+0xb3/0x1d0 kernel/time/timer.c:1747
>    __do_softirq+0x29b/0x9c2 kernel/softirq.c:558
>    invoke_softirq kernel/softirq.c:432 [inline]
>    __irq_exit_rcu+0x123/0x180 kernel/softirq.c:637
>    irq_exit_rcu+0x5/0x20 kernel/softirq.c:649
>    sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1097
>    asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638
>    bytes_is_nonzero mm/kasan/generic.c:85 [inline]
>    memory_is_nonzero mm/kasan/generic.c:102 [inline]
>    memory_is_poisoned_n mm/kasan/generic.c:128 [inline]
>    memory_is_poisoned mm/kasan/generic.c:159 [inline]
>    check_region_inline mm/kasan/generic.c:180 [inline]
>    kasan_check_range+0xde/0x180 mm/kasan/generic.c:189
>    instrument_atomic_read include/linux/instrumented.h:71 [inline]
>    atomic_long_read include/linux/atomic/atomic-instrumented.h:1265 [inline]
>    filp_close+0x22/0x170 fs/open.c:1318
>    close_files fs/file.c:403 [inline]
>    put_files_struct fs/file.c:418 [inline]
>    put_files_struct+0x1d0/0x350 fs/file.c:415
>    exit_files+0x7e/0xa0 fs/file.c:435
>    do_exit+0xaf2/0x2a30 kernel/exit.c:801
>    do_group_exit+0xd2/0x2f0 kernel/exit.c:935
>    __do_sys_exit_group kernel/exit.c:946 [inline]
>    __se_sys_exit_group kernel/exit.c:944 [inline]
>    __x64_sys_exit_group+0x3a/0x50 kernel/exit.c:944
>    do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>    do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
>    entry_SYSCALL_64_after_hwframe+0x44/0xae
> 
> 
> stack backtrace:
> CPU: 0 PID: 4486 Comm: syz-executor301 Not tainted 5.17.0-rc6-syzkaller-00184-g38f80f42147f #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> Call Trace:
>  <IRQ>
>  __dump_stack lib/dump_stack.c:88 [inline]
>  dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
>  print_irq_inversion_bug kernel/locking/lockdep.c:194 [inline]
>  check_usage_forwards kernel/locking/lockdep.c:4043 [inline]
>  mark_lock_irq kernel/locking/lockdep.c:4175 [inline]
>  mark_lock.part.0.cold+0x86/0xd8 kernel/locking/lockdep.c:4605
>  mark_lock kernel/locking/lockdep.c:4569 [inline]
>  mark_usage kernel/locking/lockdep.c:4500 [inline]
>  __lock_acquire+0x11e3/0x56c0 kernel/locking/lockdep.c:4981
>  lock_acquire kernel/locking/lockdep.c:5639 [inline]
>  lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
>  __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
>  _raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:162
>  snd_timer_interrupt.part.0+0x34/0xcf0 sound/core/timer.c:856
>  snd_timer_interrupt sound/core/timer.c:1154 [inline]
>  snd_timer_s_function+0x14b/0x200 sound/core/timer.c:1154
>  call_timer_fn+0x1a5/0x6b0 kernel/time/timer.c:1421
>  expire_timers kernel/time/timer.c:1466 [inline]
>  __run_timers.part.0+0x67c/0xa30 kernel/time/timer.c:1734
>  __run_timers kernel/time/timer.c:1715 [inline]
>  run_timer_softirq+0xb3/0x1d0 kernel/time/timer.c:1747
>  __do_softirq+0x29b/0x9c2 kernel/softirq.c:558
>  invoke_softirq kernel/softirq.c:432 [inline]
>  __irq_exit_rcu+0x123/0x180 kernel/softirq.c:637
>  irq_exit_rcu+0x5/0x20 kernel/softirq.c:649
>  sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1097
>  </IRQ>
>  <TASK>
>  asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638
> RIP: 0010:bytes_is_nonzero mm/kasan/generic.c:85 [inline]
> RIP: 0010:memory_is_nonzero mm/kasan/generic.c:102 [inline]
> RIP: 0010:memory_is_poisoned_n mm/kasan/generic.c:128 [inline]
> RIP: 0010:memory_is_poisoned mm/kasan/generic.c:159 [inline]
> RIP: 0010:check_region_inline mm/kasan/generic.c:180 [inline]
> RIP: 0010:kasan_check_range+0xde/0x180 mm/kasan/generic.c:189
> Code: 74 f2 48 89 c2 b8 01 00 00 00 48 85 d2 75 56 5b 5d 41 5c c3 48 85 d2 74 5e 48 01 ea eb 09 48 83 c0 01 48 39 d0 74 50 80 38 00 <74> f2 eb d4 41 bc 08 00 00 00 48 89 ea 45 29 dc 4d 8d 1c 2c eb 0c
> RSP: 0018:ffffc9000376fd30 EFLAGS: 00000246
> RAX: ffffed100f1d3d9f RBX: ffffed100f1d3da0 RCX: ffffffff81cb24b2
> RDX: ffffed100f1d3da0 RSI: 0000000000000008 RDI: ffff888078e9ecf8
> RBP: ffffed100f1d3d9f R08: 0000000000000000 R09: ffff888078e9ecff
> R10: ffffed100f1d3d9f R11: 0000000000000000 R12: ffff88807ee70f00
> R13: ffff888078e9ecf8 R14: ffff88807ee70f00 R15: ffff88807ee71028
>  instrument_atomic_read include/linux/instrumented.h:71 [inline]
>  atomic_long_read include/linux/atomic/atomic-instrumented.h:1265 [inline]
>  filp_close+0x22/0x170 fs/open.c:1318
>  close_files fs/file.c:403 [inline]
>  put_files_struct fs/file.c:418 [inline]
>  put_files_struct+0x1d0/0x350 fs/file.c:415
>  exit_files+0x7e/0xa0 fs/file.c:435
>  do_exit+0xaf2/0x2a30 kernel/exit.c:801
>  do_group_exit+0xd2/0x2f0 kernel/exit.c:935
>  __do_sys_exit_group kernel/exit.c:946 [inline]
>  __se_sys_exit_group kernel/exit.c:944 [inline]
>  __x64_sys_exit_group+0x3a/0x50 kernel/exit.c:944
>  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>  do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
>  entry_SYSCALL_64_after_hwframe+0x44/0xae
> RIP: 0033:0x7ff95f986c99
> Code: Unable to access opcode bytes at RIP 0x7ff95f986c6f.
> RSP: 002b:00007ffecd4a5e98 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
> RAX: ffffffffffffffda RBX: 00007ff95f9fb330 RCX: 00007ff95f986c99
> RDX: 000000000000003c RSI: 00000000000000e7 RDI: 0000000000000000
> RBP: 0000000000000000 R08: ffffffffffffffc0 R09: 0000000000000001
> R10: 0000000000000001 R11: 0000000000000246 R12: 00007ff95f9fb330
> R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000001
>  </TASK>
> ----------------
> Code disassembly (best guess):
>    0:	74 f2                	je     0xfffffff4
>    2:	48 89 c2             	mov    %rax,%rdx
>    5:	b8 01 00 00 00       	mov    $0x1,%eax
>    a:	48 85 d2             	test   %rdx,%rdx
>    d:	75 56                	jne    0x65
>    f:	5b                   	pop    %rbx
>   10:	5d                   	pop    %rbp
>   11:	41 5c                	pop    %r12
>   13:	c3                   	retq
>   14:	48 85 d2             	test   %rdx,%rdx
>   17:	74 5e                	je     0x77
>   19:	48 01 ea             	add    %rbp,%rdx
>   1c:	eb 09                	jmp    0x27
>   1e:	48 83 c0 01          	add    $0x1,%rax
>   22:	48 39 d0             	cmp    %rdx,%rax
>   25:	74 50                	je     0x77
>   27:	80 38 00             	cmpb   $0x0,(%rax)
> * 2a:	74 f2                	je     0x1e <-- trapping instruction
>   2c:	eb d4                	jmp    0x2
>   2e:	41 bc 08 00 00 00    	mov    $0x8,%r12d
>   34:	48 89 ea             	mov    %rbp,%rdx
>   37:	45 29 dc             	sub    %r11d,%r12d
>   3a:	4d 8d 1c 2c          	lea    (%r12,%rbp,1),%r11
>   3e:	eb 0c                	jmp    0x4c
> 

Walk around the deadlock by trying to lock tasklist_lock for write on
timer irq and scheduling workqueue work if any lock owner detected.

Only for thoughts now.

Hillf

#syz test: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/ 38f80f42147f

--- x/sound/core/timer.c
+++ y/sound/core/timer.c
@@ -916,7 +916,14 @@ void snd_timer_interrupt(struct snd_time
 	}
 
 	/* now process all fast callbacks */
-	snd_timer_process_callbacks(timer, &timer->ack_list_head);
+	if (write_trylock(&tasklist_lock)) {
+		write_unlock(&tasklist_lock);
+		snd_timer_process_callbacks(timer, &timer->ack_list_head);
+	} else {
+		/* go the slow path to avoid deadlock by calling kill_fasync() */
+		list_splice_init(&timer->ack_list_head,
+				 &timer->sack_list_head);
+	}
 
 	/* do we have any slow callbacks? */
 	use_work = !list_empty(&timer->sack_list_head);
--

Re: [syzbot] possible deadlock in snd_timer_interrupt (2)

[syzbot]

Hello,

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

========================================================
WARNING: possible irq lock inversion dependency detected
5.17.0-rc6-syzkaller-00184-g38f80f42147f-dirty #0 Not tainted
--------------------------------------------------------
syz-executor295/5049 just changed the state of lock:
ffff888021a6f948 (&timer->lock){..-.}-{2:2}, at: snd_timer_interrupt.part.0+0x33/0xe80 sound/core/timer.c:856
but this lock took another, SOFTIRQ-READ-unsafe lock in the past:
 (tasklist_lock){.+.+}-{2:2}


and interrupts could create inverse lock ordering between them.


other info that might help us debug this:
Chain exists of:
  &timer->lock --> &new->fa_lock --> tasklist_lock

 Possible interrupt unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(tasklist_lock);
                               local_irq_disable();
                               lock(&timer->lock);
                               lock(&new->fa_lock);
  <Interrupt>
    lock(&timer->lock);

 *** DEADLOCK ***

2 locks held by syz-executor295/5049:
 #0: ffff88801bbbc028 (&mm->mmap_lock#2){++++}-{3:3}, at: mmap_write_lock include/linux/mmap_lock.h:71 [inline]
 #0: ffff88801bbbc028 (&mm->mmap_lock#2){++++}-{3:3}, at: exit_mmap+0x10d/0x6a0 mm/mmap.c:3160
 #1: ffffc90000dc0d70 ((&priv->tlist)){+.-.}-{0:0}, at: lockdep_copy_map include/linux/lockdep.h:35 [inline]
 #1: ffffc90000dc0d70 ((&priv->tlist)){+.-.}-{0:0}, at: call_timer_fn+0xd5/0x6b0 kernel/time/timer.c:1411

the shortest dependencies between 2nd lock and 1st lock:
   -> (tasklist_lock){.+.+}-{2:2} {
      HARDIRQ-ON-R at:
                          lock_acquire kernel/locking/lockdep.c:5639 [inline]
                          lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
                          __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline]
                          _raw_read_lock+0x5b/0x70 kernel/locking/spinlock.c:228
                          do_wait+0x284/0xce0 kernel/exit.c:1518
                          kernel_wait+0x9c/0x150 kernel/exit.c:1708
                          call_usermodehelper_exec_sync kernel/umh.c:139 [inline]
                          call_usermodehelper_exec_work+0xf5/0x180 kernel/umh.c:166
                          process_one_work+0x9ac/0x1650 kernel/workqueue.c:2307
                          worker_thread+0x657/0x1110 kernel/workqueue.c:2454
                          kthread+0x2e9/0x3a0 kernel/kthread.c:377
                          ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
      SOFTIRQ-ON-R at:
                          lock_acquire kernel/locking/lockdep.c:5639 [inline]
                          lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
                          __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline]
                          _raw_read_lock+0x5b/0x70 kernel/locking/spinlock.c:228
                          do_wait+0x284/0xce0 kernel/exit.c:1518
                          kernel_wait+0x9c/0x150 kernel/exit.c:1708
                          call_usermodehelper_exec_sync kernel/umh.c:139 [inline]
                          call_usermodehelper_exec_work+0xf5/0x180 kernel/umh.c:166
                          process_one_work+0x9ac/0x1650 kernel/workqueue.c:2307
                          worker_thread+0x657/0x1110 kernel/workqueue.c:2454
                          kthread+0x2e9/0x3a0 kernel/kthread.c:377
                          ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
      INITIAL USE at:
                         lock_acquire kernel/locking/lockdep.c:5639 [inline]
                         lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
                         __raw_write_lock_irq include/linux/rwlock_api_smp.h:195 [inline]
                         _raw_write_lock_irq+0x32/0x50 kernel/locking/spinlock.c:326
                         copy_process+0x486a/0x7250 kernel/fork.c:2295
                         kernel_clone+0xe7/0xab0 kernel/fork.c:2565
                         kernel_thread+0xb5/0xf0 kernel/fork.c:2617
                         rest_init+0x23/0x3e0 init/main.c:690
                         start_kernel+0x47a/0x49b init/main.c:1138
                         secondary_startup_64_no_verify+0xc3/0xcb
      INITIAL READ USE at:
                              lock_acquire kernel/locking/lockdep.c:5639 [inline]
                              lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
                              __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline]
                              _raw_read_lock+0x5b/0x70 kernel/locking/spinlock.c:228
                              do_wait+0x284/0xce0 kernel/exit.c:1518
                              kernel_wait+0x9c/0x150 kernel/exit.c:1708
                              call_usermodehelper_exec_sync kernel/umh.c:139 [inline]
                              call_usermodehelper_exec_work+0xf5/0x180 kernel/umh.c:166
                              process_one_work+0x9ac/0x1650 kernel/workqueue.c:2307
                              worker_thread+0x657/0x1110 kernel/workqueue.c:2454
                              kthread+0x2e9/0x3a0 kernel/kthread.c:377
                              ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
    }
    ... key      at: [<ffffffff8b80a098>] tasklist_lock+0x18/0x40
    ... acquired at:
   __raw_read_lock include/linux/rwlock_api_smp.h:150 [inline]
   _raw_read_lock+0x5b/0x70 kernel/locking/spinlock.c:228
   send_sigio+0xab/0x380 fs/fcntl.c:810
   kill_fasync_rcu fs/fcntl.c:1021 [inline]
   kill_fasync fs/fcntl.c:1035 [inline]
   kill_fasync+0x1f8/0x470 fs/fcntl.c:1028
   snd_timer_user_ccallback+0x298/0x330 sound/core/timer.c:1393
   snd_timer_notify1+0x11c/0x3b0 sound/core/timer.c:516
   snd_timer_stop1+0x496/0x860 sound/core/timer.c:657
   snd_timer_stop sound/core/timer.c:710 [inline]
   snd_timer_close_locked+0x20f/0xbb0 sound/core/timer.c:408
   snd_timer_close+0x87/0xf0 sound/core/timer.c:463
   __snd_timer_user_ioctl.isra.0+0x10e2/0x2490 sound/core/timer.c:1769
   snd_timer_user_ioctl+0x77/0xb0 sound/core/timer.c:2135
   vfs_ioctl fs/ioctl.c:51 [inline]
   __do_sys_ioctl fs/ioctl.c:874 [inline]
   __se_sys_ioctl fs/ioctl.c:860 [inline]
   __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860
   do_syscall_x64 arch/x86/entry/common.c:50 [inline]
   do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
   entry_SYSCALL_64_after_hwframe+0x44/0xae

  -> (&f->f_owner.lock){....}-{2:2} {
     INITIAL USE at:
                       lock_acquire kernel/locking/lockdep.c:5639 [inline]
                       lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
                       __raw_write_lock_irq include/linux/rwlock_api_smp.h:195 [inline]
                       _raw_write_lock_irq+0x32/0x50 kernel/locking/spinlock.c:326
                       f_modown+0x2a/0x390 fs/fcntl.c:91
                       __f_setown fs/fcntl.c:110 [inline]
                       f_setown+0xd7/0x230 fs/fcntl.c:138
                       do_fcntl+0x749/0x1210 fs/fcntl.c:393
                       __do_sys_fcntl fs/fcntl.c:472 [inline]
                       __se_sys_fcntl fs/fcntl.c:457 [inline]
                       __x64_sys_fcntl+0x165/0x1e0 fs/fcntl.c:457
                       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
                       do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
                       entry_SYSCALL_64_after_hwframe+0x44/0xae
     INITIAL READ USE at:
                            lock_acquire kernel/locking/lockdep.c:5639 [inline]
                            lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
                            __raw_read_lock_irqsave include/linux/rwlock_api_smp.h:160 [inline]
                            _raw_read_lock_irqsave+0x70/0x90 kernel/locking/spinlock.c:236
                            send_sigio+0x24/0x380 fs/fcntl.c:796
                            kill_fasync_rcu fs/fcntl.c:1021 [inline]
                            kill_fasync fs/fcntl.c:1035 [inline]
                            kill_fasync+0x1f8/0x470 fs/fcntl.c:1028
                            snd_timer_user_ccallback+0x298/0x330 sound/core/timer.c:1393
                            snd_timer_notify1+0x11c/0x3b0 sound/core/timer.c:516
                            snd_timer_start1+0x4d4/0x800 sound/core/timer.c:578
                            snd_timer_start sound/core/timer.c:696 [inline]
                            snd_timer_start sound/core/timer.c:689 [inline]
                            snd_timer_user_start.isra.0+0x1e3/0x260 sound/core/timer.c:1991
                            __snd_timer_user_ioctl.isra.0+0xda8/0x2490 sound/core/timer.c:2114
                            snd_timer_user_ioctl+0x77/0xb0 sound/core/timer.c:2135
                            vfs_ioctl fs/ioctl.c:51 [inline]
                            __do_sys_ioctl fs/ioctl.c:874 [inline]
                            __se_sys_ioctl fs/ioctl.c:860 [inline]
                            __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860
                            do_syscall_x64 arch/x86/entry/common.c:50 [inline]
                            do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
                            entry_SYSCALL_64_after_hwframe+0x44/0xae
   }
   ... key      at: [<ffffffff90585a40>] __key.5+0x0/0x40
   ... acquired at:
   __raw_read_lock_irqsave include/linux/rwlock_api_smp.h:160 [inline]
   _raw_read_lock_irqsave+0x70/0x90 kernel/locking/spinlock.c:236
   send_sigio+0x24/0x380 fs/fcntl.c:796
   kill_fasync_rcu fs/fcntl.c:1021 [inline]
   kill_fasync fs/fcntl.c:1035 [inline]
   kill_fasync+0x1f8/0x470 fs/fcntl.c:1028
   snd_timer_user_ccallback+0x298/0x330 sound/core/timer.c:1393
   snd_timer_notify1+0x11c/0x3b0 sound/core/timer.c:516
   snd_timer_start1+0x4d4/0x800 sound/core/timer.c:578
   snd_timer_start sound/core/timer.c:696 [inline]
   snd_timer_start sound/core/timer.c:689 [inline]
   snd_timer_user_start.isra.0+0x1e3/0x260 sound/core/timer.c:1991
   __snd_timer_user_ioctl.isra.0+0xda8/0x2490 sound/core/timer.c:2114
   snd_timer_user_ioctl+0x77/0xb0 sound/core/timer.c:2135
   vfs_ioctl fs/ioctl.c:51 [inline]
   __do_sys_ioctl fs/ioctl.c:874 [inline]
   __se_sys_ioctl fs/ioctl.c:860 [inline]
   __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860
   do_syscall_x64 arch/x86/entry/common.c:50 [inline]
   do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
   entry_SYSCALL_64_after_hwframe+0x44/0xae

 -> (&new->fa_lock){....}-{2:2} {
    INITIAL USE at:
                     lock_acquire kernel/locking/lockdep.c:5639 [inline]
                     lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
                     __raw_write_lock_irq include/linux/rwlock_api_smp.h:195 [inline]
                     _raw_write_lock_irq+0x32/0x50 kernel/locking/spinlock.c:326
                     fasync_remove_entry+0xb6/0x1f0 fs/fcntl.c:891
                     fasync_helper+0x9e/0xb0 fs/fcntl.c:994
                     __fput+0x846/0x9f0 fs/file_table.c:314
                     task_work_run+0xdd/0x1a0 kernel/task_work.c:164
                     exit_task_work include/linux/task_work.h:32 [inline]
                     do_exit+0xb29/0x2a30 kernel/exit.c:806
                     do_group_exit+0xd2/0x2f0 kernel/exit.c:935
                     __do_sys_exit_group kernel/exit.c:946 [inline]
                     __se_sys_exit_group kernel/exit.c:944 [inline]
                     __x64_sys_exit_group+0x3a/0x50 kernel/exit.c:944
                     do_syscall_x64 arch/x86/entry/common.c:50 [inline]
                     do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
                     entry_SYSCALL_64_after_hwframe+0x44/0xae
    INITIAL READ USE at:
                          lock_acquire kernel/locking/lockdep.c:5639 [inline]
                          lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
                          __raw_read_lock_irqsave include/linux/rwlock_api_smp.h:160 [inline]
                          _raw_read_lock_irqsave+0x70/0x90 kernel/locking/spinlock.c:236
                          kill_fasync_rcu fs/fcntl.c:1014 [inline]
                          kill_fasync fs/fcntl.c:1035 [inline]
                          kill_fasync+0x136/0x470 fs/fcntl.c:1028
                          snd_timer_user_ccallback+0x298/0x330 sound/core/timer.c:1393
                          snd_timer_notify1+0x11c/0x3b0 sound/core/timer.c:516
                          snd_timer_start1+0x4d4/0x800 sound/core/timer.c:578
                          snd_timer_start sound/core/timer.c:696 [inline]
                          snd_timer_start sound/core/timer.c:689 [inline]
                          snd_timer_user_start.isra.0+0x1e3/0x260 sound/core/timer.c:1991
                          __snd_timer_user_ioctl.isra.0+0xda8/0x2490 sound/core/timer.c:2114
                          snd_timer_user_ioctl+0x77/0xb0 sound/core/timer.c:2135
                          vfs_ioctl fs/ioctl.c:51 [inline]
                          __do_sys_ioctl fs/ioctl.c:874 [inline]
                          __se_sys_ioctl fs/ioctl.c:860 [inline]
                          __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860
                          do_syscall_x64 arch/x86/entry/common.c:50 [inline]
                          do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
                          entry_SYSCALL_64_after_hwframe+0x44/0xae
  }
  ... key      at: [<ffffffff90586820>] __key.0+0x0/0x40
  ... acquired at:
   __raw_read_lock_irqsave include/linux/rwlock_api_smp.h:160 [inline]
   _raw_read_lock_irqsave+0x70/0x90 kernel/locking/spinlock.c:236
   kill_fasync_rcu fs/fcntl.c:1014 [inline]
   kill_fasync fs/fcntl.c:1035 [inline]
   kill_fasync+0x136/0x470 fs/fcntl.c:1028
   snd_timer_user_ccallback+0x298/0x330 sound/core/timer.c:1393
   snd_timer_notify1+0x11c/0x3b0 sound/core/timer.c:516
   snd_timer_start1+0x4d4/0x800 sound/core/timer.c:578
   snd_timer_start sound/core/timer.c:696 [inline]
   snd_timer_start sound/core/timer.c:689 [inline]
   snd_timer_user_start.isra.0+0x1e3/0x260 sound/core/timer.c:1991
   __snd_timer_user_ioctl.isra.0+0xda8/0x2490 sound/core/timer.c:2114
   snd_timer_user_ioctl+0x77/0xb0 sound/core/timer.c:2135
   vfs_ioctl fs/ioctl.c:51 [inline]
   __do_sys_ioctl fs/ioctl.c:874 [inline]
   __se_sys_ioctl fs/ioctl.c:860 [inline]
   __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860
   do_syscall_x64 arch/x86/entry/common.c:50 [inline]
   do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
   entry_SYSCALL_64_after_hwframe+0x44/0xae

-> (&timer->lock){..-.}-{2:2} {
   IN-SOFTIRQ-W at:
                    lock_acquire kernel/locking/lockdep.c:5639 [inline]
                    lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
                    __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
                    _raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:162
                    snd_timer_interrupt.part.0+0x33/0xe80 sound/core/timer.c:856
                    snd_timer_interrupt sound/core/timer.c:1161 [inline]
                    snd_timer_s_function+0x14b/0x200 sound/core/timer.c:1161
                    call_timer_fn+0x1a5/0x6b0 kernel/time/timer.c:1421
                    expire_timers kernel/time/timer.c:1466 [inline]
                    __run_timers.part.0+0x67c/0xa30 kernel/time/timer.c:1734
                    __run_timers kernel/time/timer.c:1715 [inline]
                    run_timer_softirq+0xb3/0x1d0 kernel/time/timer.c:1747
                    __do_softirq+0x29b/0x9c2 kernel/softirq.c:558
                    invoke_softirq kernel/softirq.c:432 [inline]
                    __irq_exit_rcu+0x123/0x180 kernel/softirq.c:637
                    irq_exit_rcu+0x5/0x20 kernel/softirq.c:649
                    sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1097
                    asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638
                    native_save_fl arch/x86/include/asm/irqflags.h:29 [inline]
                    arch_local_save_flags arch/x86/include/asm/irqflags.h:70 [inline]
                    arch_local_irq_save arch/x86/include/asm/irqflags.h:106 [inline]
                    lock_is_held_type+0x51/0x140 kernel/locking/lockdep.c:5678
                    lock_is_held include/linux/lockdep.h:283 [inline]
                    __might_resched+0x3a/0x2c0 kernel/sched/core.c:9547
                    down_write+0x6c/0x150 kernel/locking/rwsem.c:1513
                    i_mmap_lock_write include/linux/fs.h:492 [inline]
                    unlink_file_vma+0x7d/0x110 mm/mmap.c:170
                    free_pgtables+0x1b3/0x2f0 mm/memory.c:428
                    exit_mmap+0x210/0x6a0 mm/mmap.c:3179
                    __mmput+0x122/0x4b0 kernel/fork.c:1114
                    mmput+0x56/0x60 kernel/fork.c:1135
                    exit_mm kernel/exit.c:507 [inline]
                    do_exit+0xa3c/0x2a30 kernel/exit.c:793
                    do_group_exit+0xd2/0x2f0 kernel/exit.c:935
                    __do_sys_exit_group kernel/exit.c:946 [inline]
                    __se_sys_exit_group kernel/exit.c:944 [inline]
                    __x64_sys_exit_group+0x3a/0x50 kernel/exit.c:944
                    do_syscall_x64 arch/x86/entry/common.c:50 [inline]
                    do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
                    entry_SYSCALL_64_after_hwframe+0x44/0xae
   INITIAL USE at:
                   lock_acquire kernel/locking/lockdep.c:5639 [inline]
                   lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
                   __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
                   _raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:162
                   snd_timer_notify sound/core/timer.c:1093 [inline]
                   snd_timer_notify+0x10c/0x3d0 sound/core/timer.c:1080
                   snd_pcm_timer_notify sound/core/pcm_native.c:608 [inline]
                   snd_pcm_post_stop+0x195/0x1f0 sound/core/pcm_native.c:1466
                   snd_pcm_action_single sound/core/pcm_native.c:1242 [inline]
                   snd_pcm_action+0x143/0x170 sound/core/pcm_native.c:1323
                   snd_pcm_stop sound/core/pcm_native.c:1489 [inline]
                   snd_pcm_drop+0x1ab/0x320 sound/core/pcm_native.c:2168
                   snd_pcm_kernel_ioctl+0x2af/0x310 sound/core/pcm_native.c:3395
                   snd_pcm_oss_sync+0x230/0x800 sound/core/oss/pcm_oss.c:1734
                   snd_pcm_oss_release+0x276/0x300 sound/core/oss/pcm_oss.c:2584
                   __fput+0x286/0x9f0 fs/file_table.c:317
                   task_work_run+0xdd/0x1a0 kernel/task_work.c:164
                   tracehook_notify_resume include/linux/tracehook.h:188 [inline]
                   exit_to_user_mode_loop kernel/entry/common.c:175 [inline]
                   exit_to_user_mode_prepare+0x27e/0x290 kernel/entry/common.c:207
                   __syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline]
                   syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:300
                   do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86
                   entry_SYSCALL_64_after_hwframe+0x44/0xae
 }
 ... key      at: [<ffffffff908843c0>] __key.12+0x0/0x40
 ... acquired at:
   mark_lock kernel/locking/lockdep.c:4569 [inline]
   mark_usage kernel/locking/lockdep.c:4500 [inline]
   __lock_acquire+0x11e3/0x56c0 kernel/locking/lockdep.c:4981
   lock_acquire kernel/locking/lockdep.c:5639 [inline]
   lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
   __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
   _raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:162
   snd_timer_interrupt.part.0+0x33/0xe80 sound/core/timer.c:856
   snd_timer_interrupt sound/core/timer.c:1161 [inline]
   snd_timer_s_function+0x14b/0x200 sound/core/timer.c:1161
   call_timer_fn+0x1a5/0x6b0 kernel/time/timer.c:1421
   expire_timers kernel/time/timer.c:1466 [inline]
   __run_timers.part.0+0x67c/0xa30 kernel/time/timer.c:1734
   __run_timers kernel/time/timer.c:1715 [inline]
   run_timer_softirq+0xb3/0x1d0 kernel/time/timer.c:1747
   __do_softirq+0x29b/0x9c2 kernel/softirq.c:558
   invoke_softirq kernel/softirq.c:432 [inline]
   __irq_exit_rcu+0x123/0x180 kernel/softirq.c:637
   irq_exit_rcu+0x5/0x20 kernel/softirq.c:649
   sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1097
   asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638
   native_save_fl arch/x86/include/asm/irqflags.h:29 [inline]
   arch_local_save_flags arch/x86/include/asm/irqflags.h:70 [inline]
   arch_local_irq_save arch/x86/include/asm/irqflags.h:106 [inline]
   lock_is_held_type+0x51/0x140 kernel/locking/lockdep.c:5678
   lock_is_held include/linux/lockdep.h:283 [inline]
   __might_resched+0x3a/0x2c0 kernel/sched/core.c:9547
   down_write+0x6c/0x150 kernel/locking/rwsem.c:1513
   i_mmap_lock_write include/linux/fs.h:492 [inline]
   unlink_file_vma+0x7d/0x110 mm/mmap.c:170
   free_pgtables+0x1b3/0x2f0 mm/memory.c:428
   exit_mmap+0x210/0x6a0 mm/mmap.c:3179
   __mmput+0x122/0x4b0 kernel/fork.c:1114
   mmput+0x56/0x60 kernel/fork.c:1135
   exit_mm kernel/exit.c:507 [inline]
   do_exit+0xa3c/0x2a30 kernel/exit.c:793
   do_group_exit+0xd2/0x2f0 kernel/exit.c:935
   __do_sys_exit_group kernel/exit.c:946 [inline]
   __se_sys_exit_group kernel/exit.c:944 [inline]
   __x64_sys_exit_group+0x3a/0x50 kernel/exit.c:944
   do_syscall_x64 arch/x86/entry/common.c:50 [inline]
   do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
   entry_SYSCALL_64_after_hwframe+0x44/0xae


stack backtrace:
CPU: 1 PID: 5049 Comm: syz-executor295 Not tainted 5.17.0-rc6-syzkaller-00184-g38f80f42147f-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
 print_irq_inversion_bug kernel/locking/lockdep.c:194 [inline]
 check_usage_forwards kernel/locking/lockdep.c:4043 [inline]
 mark_lock_irq kernel/locking/lockdep.c:4175 [inline]
 mark_lock.part.0.cold+0x86/0xd8 kernel/locking/lockdep.c:4605
 mark_lock kernel/locking/lockdep.c:4569 [inline]
 mark_usage kernel/locking/lockdep.c:4500 [inline]
 __lock_acquire+0x11e3/0x56c0 kernel/locking/lockdep.c:4981
 lock_acquire kernel/locking/lockdep.c:5639 [inline]
 lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:162
 snd_timer_interrupt.part.0+0x33/0xe80 sound/core/timer.c:856
 snd_timer_interrupt sound/core/timer.c:1161 [inline]
 snd_timer_s_function+0x14b/0x200 sound/core/timer.c:1161
 call_timer_fn+0x1a5/0x6b0 kernel/time/timer.c:1421
 expire_timers kernel/time/timer.c:1466 [inline]
 __run_timers.part.0+0x67c/0xa30 kernel/time/timer.c:1734
 __run_timers kernel/time/timer.c:1715 [inline]
 run_timer_softirq+0xb3/0x1d0 kernel/time/timer.c:1747
 __do_softirq+0x29b/0x9c2 kernel/softirq.c:558
 invoke_softirq kernel/softirq.c:432 [inline]
 __irq_exit_rcu+0x123/0x180 kernel/softirq.c:637
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:649
 sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1097
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638
RIP: 0010:native_save_fl arch/x86/include/asm/irqflags.h:29 [inline]
RIP: 0010:arch_local_save_flags arch/x86/include/asm/irqflags.h:70 [inline]
RIP: 0010:arch_local_irq_save arch/x86/include/asm/irqflags.h:106 [inline]
RIP: 0010:lock_is_held_type+0x51/0x140 kernel/locking/lockdep.c:5678
Code: b6 76 85 c0 0f 85 ca 00 00 00 65 4c 8b 24 25 00 70 02 00 41 8b 94 24 5c 0a 00 00 85 d2 0f 85 b1 00 00 00 48 89 fd 41 89 f6 9c <8f> 04 24 fa 48 c7 c7 e0 60 ac 89 31 db e8 fd 0d 00 00 41 8b 84 24
RSP: 0018:ffffc9000333fb08 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000001
RDX: 0000000000000000 RSI: 00000000ffffffff RDI: ffffffff8bb84520
RBP: ffffffff8bb84520 R08: 0000000000000000 R09: ffffffff8ffc4977
R10: 0000000000000001 R11: 0000000000000000 R12: ffff888022f40000
R13: 00000000ffffffff R14: 00000000ffffffff R15: 0000000000000000
 lock_is_held include/linux/lockdep.h:283 [inline]
 __might_resched+0x3a/0x2c0 kernel/sched/core.c:9547
 down_write+0x6c/0x150 kernel/locking/rwsem.c:1513
 i_mmap_lock_write include/linux/fs.h:492 [inline]
 unlink_file_vma+0x7d/0x110 mm/mmap.c:170
 free_pgtables+0x1b3/0x2f0 mm/memory.c:428
 exit_mmap+0x210/0x6a0 mm/mmap.c:3179
 __mmput+0x122/0x4b0 kernel/fork.c:1114
 mmput+0x56/0x60 kernel/fork.c:1135
 exit_mm kernel/exit.c:507 [inline]
 do_exit+0xa3c/0x2a30 kernel/exit.c:793
 do_group_exit+0xd2/0x2f0 kernel/exit.c:935
 __do_sys_exit_group kernel/exit.c:946 [inline]
 __se_sys_exit_group kernel/exit.c:944 [inline]
 __x64_sys_exit_group+0x3a/0x50 kernel/exit.c:944
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7fa5e94ccc89
Code: Unable to access opcode bytes at RIP 0x7fa5e94ccc5f.
RSP: 002b:00007ffe3ea446b8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 00007fa5e9541330 RCX: 00007fa5e94ccc89
RDX: 000000000000003c RSI: 00000000000000e7 RDI: 0000000000000000
RBP: 0000000000000000 R08: ffffffffffffffc0 R09: 0000000000000001
R10: 0000000000000001 R11: 0000000000000246 R12: 00007fa5e9541330
R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000001
 </TASK>
----------------
Code disassembly (best guess):
   0:	b6 76                	mov    $0x76,%dh
   2:	85 c0                	test   %eax,%eax
   4:	0f 85 ca 00 00 00    	jne    0xd4
   a:	65 4c 8b 24 25 00 70 	mov    %gs:0x27000,%r12
  11:	02 00
  13:	41 8b 94 24 5c 0a 00 	mov    0xa5c(%r12),%edx
  1a:	00
  1b:	85 d2                	test   %edx,%edx
  1d:	0f 85 b1 00 00 00    	jne    0xd4
  23:	48 89 fd             	mov    %rdi,%rbp
  26:	41 89 f6             	mov    %esi,%r14d
  29:	9c                   	pushfq
* 2a:	8f 04 24             	popq   (%rsp) <-- trapping instruction
  2d:	fa                   	cli
  2e:	48 c7 c7 e0 60 ac 89 	mov    $0xffffffff89ac60e0,%rdi
  35:	31 db                	xor    %ebx,%ebx
  37:	e8 fd 0d 00 00       	callq  0xe39
  3c:	41                   	rex.B
  3d:	8b                   	.byte 0x8b
  3e:	84                   	.byte 0x84
  3f:	24                   	.byte 0x24


Tested on:

commit:         38f80f42 MAINTAINERS: Remove dead patchwork link
git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/
console output: https://syzkaller.appspot.com/x/log.txt?x=17ec0c11700000
kernel config:  https://syzkaller.appspot.com/x/.config?x=4e9585407e09f75f
dashboard link: https://syzkaller.appspot.com/bug?extid=1ee0910eca9c94f71f25
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
patch:          https://syzkaller.appspot.com/x/patch.diff?x=15000f85700000

Re: [syzbot] possible deadlock in snd_timer_interrupt (2)

[Takashi Iwai]

On Mon, 07 Mar 2022 09:05:20 +0100,
Hillf Danton wrote:
> 
> Walk around the deadlock by trying to lock tasklist_lock for write on
> timer irq and scheduling workqueue work if any lock owner detected.

Oh no, that's toooo ugly.

And  the problem isn't only here; take a look at commits f671a691e299
and 2f488f698fda.  There are other users of kill_fasync() with the
hard-IRQ disabled, too.

So, IMO, the handling of tasklist_lock around kill_fasync() looks
broken and the fix should be needed there (or other core part),
instead of messing round each caller's code.


thanks,

Takashi

> 
> Only for thoughts now.
> 
> Hillf
> 
> #syz test: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/ 38f80f42147f
> 
> --- x/sound/core/timer.c
> +++ y/sound/core/timer.c
> @@ -916,7 +916,14 @@ void snd_timer_interrupt(struct snd_time
>  	}
>  
>  	/* now process all fast callbacks */
> -	snd_timer_process_callbacks(timer, &timer->ack_list_head);
> +	if (write_trylock(&tasklist_lock)) {
> +		write_unlock(&tasklist_lock);
> +		snd_timer_process_callbacks(timer, &timer->ack_list_head);
> +	} else {
> +		/* go the slow path to avoid deadlock by calling kill_fasync() */
> +		list_splice_init(&timer->ack_list_head,
> +				 &timer->sack_list_head);
> +	}
>  
>  	/* do we have any slow callbacks? */
>  	use_work = !list_empty(&timer->sack_list_head);
> --
> 

Re: [syzbot] possible deadlock in snd_timer_interrupt (2)

[Hillf Danton]

On Mon, 07 Mar 2022 09:31:16 +0100 Takashi Iwai wrote:
> On Mon, 07 Mar 2022 09:05:20 +0100 Hillf Danton wrote:
> > 
> > Walk around the deadlock by trying to lock tasklist_lock for write on
> > timer irq and scheduling workqueue work if any lock owner detected.
> 
> Oh no, that's toooo ugly.
> 
> And  the problem isn't only here; take a look at commits f671a691e299
> and 2f488f698fda.  There are other users of kill_fasync() with the
> hard-IRQ disabled, too.
> 
> So, IMO, the handling of tasklist_lock around kill_fasync() looks
> broken and the fix should be needed there (or other core part),
> instead of messing round each caller's code.

In addition to hard-IRQ mentioned above, it is a global rwlock reported
in this case rather than the non-global locks addressed in the commits
above and thus we need different fix.

Replace it with rcu read lock.

Hillf

#syz test: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/ 38f80f42147f

--- x/fs/fcntl.c
+++ y/fs/fcntl.c
@@ -807,11 +807,11 @@ void send_sigio(struct fown_struct *fown
 			send_sigio_to_task(p, fown, fd, band, type);
 		rcu_read_unlock();
 	} else {
-		read_lock(&tasklist_lock);
+		rcu_read_lock();
 		do_each_pid_task(pid, type, p) {
 			send_sigio_to_task(p, fown, fd, band, type);
 		} while_each_pid_task(pid, type, p);
-		read_unlock(&tasklist_lock);
+		rcu_read_unlock();
 	}
  out_unlock_fown:
 	read_unlock_irqrestore(&fown->lock, flags);
--

Re: [syzbot] possible deadlock in snd_timer_interrupt (2)

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+1ee0910eca9c94f71f25@syzkaller.appspotmail.com

Tested on:

commit:         38f80f42 MAINTAINERS: Remove dead patchwork link
git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/
kernel config:  https://syzkaller.appspot.com/x/.config?x=4e9585407e09f75f
dashboard link: https://syzkaller.appspot.com/bug?extid=1ee0910eca9c94f71f25
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
patch:          https://syzkaller.appspot.com/x/patch.diff?x=16c1baa1700000

Note: testing is done by a robot and is best-effort only.