Hello, syzbot found the following issue on: HEAD commit: dff9f829 Add linux-next specific files for 20200908 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=17521b35900000 kernel config: https://syzkaller.appspot.com/x/.config?x=37b3426c77bda44c dashboard link: https://syzkaller.appspot.com/bug?extid=907b8537e3b0e55151fc compiler: gcc (GCC) 10.1.0-syz 20200507 Unfortunately, I don't have any reproducer for this issue yet. IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+907b8537e3b0e55151fc@xxxxxxxxxxxxxxxxxxxxxxxxx ===================================================== WARNING: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected 5.9.0-rc4-next-20200908-syzkaller #0 Not tainted ----------------------------------------------------- syz-executor.5/15112 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire: ffff8880a828e478 (&f->f_owner.lock){.+.?}-{2:2}, at: send_sigio+0x24/0x320 fs/fcntl.c:786 and this task is already holding: ffff88809d98b9f0 (&new->fa_lock){....}-{2:2}, at: kill_fasync_rcu fs/fcntl.c:1002 [inline] ffff88809d98b9f0 (&new->fa_lock){....}-{2:2}, at: kill_fasync fs/fcntl.c:1023 [inline] ffff88809d98b9f0 (&new->fa_lock){....}-{2:2}, at: kill_fasync+0x14b/0x460 fs/fcntl.c:1016 which would create a new lock dependency: (&new->fa_lock){....}-{2:2} -> (&f->f_owner.lock){.+.?}-{2:2} but this new dependency connects a SOFTIRQ-irq-safe lock: (fasync_lock){+.+.}-{2:2} ... which became SOFTIRQ-irq-safe at: lock_acquire+0x1f3/0xaf0 kernel/locking/lockdep.c:5398 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151 spin_lock include/linux/spinlock.h:354 [inline] fasync_remove_entry+0x2e/0x1f0 fs/fcntl.c:875 fasync_helper+0x9e/0xb0 fs/fcntl.c:983 __tty_fasync drivers/tty/tty_io.c:2126 [inline] tty_release+0x16d/0xf60 drivers/tty/tty_io.c:1664 __fput+0x285/0x920 fs/file_table.c:281 task_work_run+0xdd/0x190 kernel/task_work.c:141 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_user_mode_loop kernel/entry/common.c:163 [inline] exit_to_user_mode_prepare+0x1e2/0x1f0 kernel/entry/common.c:190 syscall_exit_to_user_mode+0x7e/0x2e0 kernel/entry/common.c:265 entry_SYSCALL_64_after_hwframe+0x44/0xa9 to a SOFTIRQ-irq-unsafe lock: (&f->f_owner.lock){.+.?}-{2:2} ... which became SOFTIRQ-irq-unsafe at: ... lock_acquire+0x1f3/0xaf0 kernel/locking/lockdep.c:5398 __raw_read_lock include/linux/rwlock_api_smp.h:149 [inline] _raw_read_lock+0x36/0x70 kernel/locking/spinlock.c:223 send_sigurg+0x1e/0xa60 fs/fcntl.c:824 sk_send_sigurg+0x76/0x300 net/core/sock.c:2930 tcp_check_urg.isra.0+0x1f4/0x710 net/ipv4/tcp_input.c:5485 tcp_urg net/ipv4/tcp_input.c:5526 [inline] tcp_rcv_established+0x10b9/0x1eb0 net/ipv4/tcp_input.c:5858 tcp_v4_do_rcv+0x5d1/0x870 net/ipv4/tcp_ipv4.c:1643 tcp_v4_rcv+0x2d10/0x3750 net/ipv4/tcp_ipv4.c:2025 ip_protocol_deliver_rcu+0x5c/0x880 net/ipv4/ip_input.c:204 ip_local_deliver_finish+0x20a/0x370 net/ipv4/ip_input.c:231 NF_HOOK include/linux/netfilter.h:301 [inline] NF_HOOK include/linux/netfilter.h:295 [inline] ip_local_deliver+0x1b3/0x200 net/ipv4/ip_input.c:252 dst_input include/net/dst.h:449 [inline] ip_rcv_finish+0x1da/0x2f0 net/ipv4/ip_input.c:428 NF_HOOK include/linux/netfilter.h:301 [inline] NF_HOOK include/linux/netfilter.h:295 [inline] ip_rcv+0xaa/0xd0 net/ipv4/ip_input.c:539 __netif_receive_skb_one_core+0x114/0x180 net/core/dev.c:5286 __netif_receive_skb+0x27/0x1c0 net/core/dev.c:5400 process_backlog+0x2e1/0x8e0 net/core/dev.c:6242 napi_poll net/core/dev.c:6688 [inline] net_rx_action+0x4f8/0xf90 net/core/dev.c:6758 __do_softirq+0x1f7/0xa91 kernel/softirq.c:298 run_ksoftirqd kernel/softirq.c:652 [inline] run_ksoftirqd+0xcf/0x170 kernel/softirq.c:644 smpboot_thread_fn+0x655/0x9e0 kernel/smpboot.c:165 kthread+0x3af/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 other info that might help us debug this: Chain exists of: fasync_lock --> &new->fa_lock --> &f->f_owner.lock Possible interrupt unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&f->f_owner.lock); local_irq_disable(); lock(fasync_lock); lock(&new->fa_lock); <Interrupt> lock(fasync_lock); *** DEADLOCK *** 8 locks held by syz-executor.5/15112: #0: ffff88809cee8160 (&evdev->mutex){+.+.}-{3:3}, at: evdev_write+0x1cd/0x750 drivers/input/evdev.c:513 #1: ffff88809da12230 (&dev->event_lock){-...}-{2:2}, at: input_inject_event+0xa6/0x310 drivers/input/input.c:466 #2: ffffffff89c68540 (rcu_read_lock){....}-{1:2}, at: is_event_supported drivers/input/input.c:53 [inline] #2: ffffffff89c68540 (rcu_read_lock){....}-{1:2}, at: is_event_supported drivers/input/input.c:50 [inline] #2: ffffffff89c68540 (rcu_read_lock){....}-{1:2}, at: input_inject_event+0x92/0x310 drivers/input/input.c:465 #3: ffffffff89c68540 (rcu_read_lock){....}-{1:2}, at: input_pass_values.part.0+0x0/0x700 drivers/input/input.c:833 #4: ffffffff89c68540 (rcu_read_lock){....}-{1:2}, at: evdev_events+0x55/0x330 drivers/input/evdev.c:297 #5: ffff888097fef028 (&client->buffer_lock){....}-{2:2}, at: spin_lock include/linux/spinlock.h:354 [inline] #5: ffff888097fef028 (&client->buffer_lock){....}-{2:2}, at: evdev_pass_values+0x195/0xa30 drivers/input/evdev.c:262 #6: ffffffff89c68540 (rcu_read_lock){....}-{1:2}, at: kill_fasync+0x3d/0x460 fs/fcntl.c:1021 #7: ffff88809d98b9f0 (&new->fa_lock){....}-{2:2}, at: kill_fasync_rcu fs/fcntl.c:1002 [inline] #7: ffff88809d98b9f0 (&new->fa_lock){....}-{2:2}, at: kill_fasync fs/fcntl.c:1023 [inline] #7: ffff88809d98b9f0 (&new->fa_lock){....}-{2:2}, at: kill_fasync+0x14b/0x460 fs/fcntl.c:1016 the dependencies between SOFTIRQ-irq-safe lock and the holding lock: -> (fasync_lock){+.+.}-{2:2} { HARDIRQ-ON-W at: lock_acquire+0x1f3/0xaf0 kernel/locking/lockdep.c:5398 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151 spin_lock include/linux/spinlock.h:354 [inline] fasync_remove_entry+0x2e/0x1f0 fs/fcntl.c:875 fasync_helper+0x9e/0xb0 fs/fcntl.c:983 __tty_fasync drivers/tty/tty_io.c:2126 [inline] tty_release+0x16d/0xf60 drivers/tty/tty_io.c:1664 __fput+0x285/0x920 fs/file_table.c:281 task_work_run+0xdd/0x190 kernel/task_work.c:141 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_user_mode_loop kernel/entry/common.c:163 [inline] exit_to_user_mode_prepare+0x1e2/0x1f0 kernel/entry/common.c:190 syscall_exit_to_user_mode+0x7e/0x2e0 kernel/entry/common.c:265 entry_SYSCALL_64_after_hwframe+0x44/0xa9 SOFTIRQ-ON-W at: lock_acquire+0x1f3/0xaf0 kernel/locking/lockdep.c:5398 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151 spin_lock include/linux/spinlock.h:354 [inline] fasync_remove_entry+0x2e/0x1f0 fs/fcntl.c:875 fasync_helper+0x9e/0xb0 fs/fcntl.c:983 __tty_fasync drivers/tty/tty_io.c:2126 [inline] tty_release+0x16d/0xf60 drivers/tty/tty_io.c:1664 __fput+0x285/0x920 fs/file_table.c:281 task_work_run+0xdd/0x190 kernel/task_work.c:141 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_user_mode_loop kernel/entry/common.c:163 [inline] exit_to_user_mode_prepare+0x1e2/0x1f0 kernel/entry/common.c:190 syscall_exit_to_user_mode+0x7e/0x2e0 kernel/entry/common.c:265 entry_SYSCALL_64_after_hwframe+0x44/0xa9 INITIAL USE at: lock_acquire+0x1f3/0xaf0 kernel/locking/lockdep.c:5398 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151 spin_lock include/linux/spinlock.h:354 [inline] fasync_remove_entry+0x2e/0x1f0 fs/fcntl.c:875 fasync_helper+0x9e/0xb0 fs/fcntl.c:983 __tty_fasync drivers/tty/tty_io.c:2126 [inline] tty_release+0x16d/0xf60 drivers/tty/tty_io.c:1664 __fput+0x285/0x920 fs/file_table.c:281 task_work_run+0xdd/0x190 kernel/task_work.c:141 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_user_mode_loop kernel/entry/common.c:163 [inline] exit_to_user_mode_prepare+0x1e2/0x1f0 kernel/entry/common.c:190 syscall_exit_to_user_mode+0x7e/0x2e0 kernel/entry/common.c:265 entry_SYSCALL_64_after_hwframe+0x44/0xa9 } ... key at: [<ffffffff89d445f8>] fasync_lock+0x18/0x660 ... acquired at: __raw_write_lock_irq include/linux/rwlock_api_smp.h:196 [inline] _raw_write_lock_irq+0x94/0xd0 kernel/locking/spinlock.c:311 fasync_remove_entry+0xb6/0x1f0 fs/fcntl.c:880 fasync_helper+0x9e/0xb0 fs/fcntl.c:983 lease_modify fs/locks.c:1522 [inline] lease_modify+0x28a/0x370 fs/locks.c:1509 locks_remove_lease fs/locks.c:2770 [inline] locks_remove_file+0x2be/0x580 fs/locks.c:2795 __fput+0x1b8/0x920 fs/file_table.c:273 task_work_run+0xdd/0x190 kernel/task_work.c:141 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_user_mode_loop kernel/entry/common.c:163 [inline] exit_to_user_mode_prepare+0x1e2/0x1f0 kernel/entry/common.c:190 syscall_exit_to_user_mode+0x7e/0x2e0 kernel/entry/common.c:265 entry_SYSCALL_64_after_hwframe+0x44/0xa9 -> (&new->fa_lock){....}-{2:2} { INITIAL USE at: lock_acquire+0x1f3/0xaf0 kernel/locking/lockdep.c:5398 __raw_write_lock_irq include/linux/rwlock_api_smp.h:196 [inline] _raw_write_lock_irq+0x94/0xd0 kernel/locking/spinlock.c:311 fasync_remove_entry+0xb6/0x1f0 fs/fcntl.c:880 fasync_helper+0x9e/0xb0 fs/fcntl.c:983 lease_modify fs/locks.c:1522 [inline] lease_modify+0x28a/0x370 fs/locks.c:1509 locks_remove_lease fs/locks.c:2770 [inline] locks_remove_file+0x2be/0x580 fs/locks.c:2795 __fput+0x1b8/0x920 fs/file_table.c:273 task_work_run+0xdd/0x190 kernel/task_work.c:141 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_user_mode_loop kernel/entry/common.c:163 [inline] exit_to_user_mode_prepare+0x1e2/0x1f0 kernel/entry/common.c:190 syscall_exit_to_user_mode+0x7e/0x2e0 kernel/entry/common.c:265 entry_SYSCALL_64_after_hwframe+0x44/0xa9 (null) at: general protection fault, probably for non-canonical address 0xdffffc0000000002: 0000 [#1] PREEMPT SMP KASAN KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017] CPU: 0 PID: 15112 Comm: syz-executor.5 Not tainted 5.9.0-rc4-next-20200908-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:print_lock_trace kernel/locking/lockdep.c:1751 [inline] RIP: 0010:print_lock_class_header kernel/locking/lockdep.c:2240 [inline] RIP: 0010:print_shortest_lock_dependencies.cold+0x110/0x2af kernel/locking/lockdep.c:2263 Code: 48 8b 04 24 48 c1 e8 03 42 80 3c 20 00 74 09 48 8b 3c 24 e8 dd fb de f9 48 8b 04 24 48 8b 00 48 8d 78 14 48 89 fa 48 c1 ea 03 <42> 0f b6 0c 22 48 89 fa 83 e2 07 83 c2 03 38 ca 7c 08 84 c9 0f 85 RSP: 0018:ffffc900057875c0 EFLAGS: 00010003 RAX: 0000000000000001 RBX: ffffc90005787718 RCX: 0000000000000000 RDX: 0000000000000002 RSI: ffffffff815bc817 RDI: 0000000000000015 RBP: ffffc90005787718 R08: 0000000000000004 R09: ffff8880ae620f8b R10: 0000000000000000 R11: 6c6c756e28202020 R12: dffffc0000000000 R13: ffffffff8c709bb8 R14: 0000000000000009 R15: 0000000000000000 FS: 00007f7930053700(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000004e9cf0 CR3: 000000008f8ef000 CR4: 00000000001506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: print_bad_irq_dependency kernel/locking/lockdep.c:2395 [inline] check_irq_usage.cold+0x42d/0x5b0 kernel/locking/lockdep.c:2634 check_prev_add kernel/locking/lockdep.c:2823 [inline] check_prevs_add kernel/locking/lockdep.c:2944 [inline] validate_chain kernel/locking/lockdep.c:3562 [inline] __lock_acquire+0x2800/0x55d0 kernel/locking/lockdep.c:4796 lock_acquire+0x1f3/0xaf0 kernel/locking/lockdep.c:5398 __raw_read_lock include/linux/rwlock_api_smp.h:149 [inline] _raw_read_lock+0x5b/0x70 kernel/locking/spinlock.c:223 send_sigio+0x24/0x320 fs/fcntl.c:786 kill_fasync_rcu fs/fcntl.c:1009 [inline] kill_fasync fs/fcntl.c:1023 [inline] kill_fasync+0x205/0x460 fs/fcntl.c:1016 __pass_event drivers/input/evdev.c:240 [inline] evdev_pass_values+0x715/0xa30 drivers/input/evdev.c:279 evdev_events+0x20c/0x330 drivers/input/evdev.c:307 input_to_handler+0x2a0/0x4c0 drivers/input/input.c:115 input_pass_values.part.0+0x284/0x700 drivers/input/input.c:145 input_pass_values drivers/input/input.c:134 [inline] input_handle_event+0x324/0x1390 drivers/input/input.c:399 input_inject_event+0x2f5/0x310 drivers/input/input.c:471 evdev_write+0x424/0x750 drivers/input/evdev.c:530 vfs_write+0x28e/0x700 fs/read_write.c:593 ksys_write+0x1ee/0x250 fs/read_write.c:648 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45d5b9 Code: 5d b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 2b b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f7930052c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000038f80 RCX: 000000000045d5b9 RDX: 0000000000000373 RSI: 0000000020000040 RDI: 0000000000000003 RBP: 000000000118cf80 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118cf4c R13: 00007ffe25f626af R14: 00007f79300539c0 R15: 000000000118cf4c Modules linked in: ---[ end trace 7926691370b595f2 ]--- RIP: 0010:print_lock_trace kernel/locking/lockdep.c:1751 [inline] RIP: 0010:print_lock_class_header kernel/locking/lockdep.c:2240 [inline] RIP: 0010:print_shortest_lock_dependencies.cold+0x110/0x2af kernel/locking/lockdep.c:2263 Code: 48 8b 04 24 48 c1 e8 03 42 80 3c 20 00 74 09 48 8b 3c 24 e8 dd fb de f9 48 8b 04 24 48 8b 00 48 8d 78 14 48 89 fa 48 c1 ea 03 <42> 0f b6 0c 22 48 89 fa 83 e2 07 83 c2 03 38 ca 7c 08 84 c9 0f 85 RSP: 0018:ffffc900057875c0 EFLAGS: 00010003 RAX: 0000000000000001 RBX: ffffc90005787718 RCX: 0000000000000000 RDX: 0000000000000002 RSI: ffffffff815bc817 RDI: 0000000000000015 RBP: ffffc90005787718 R08: 0000000000000004 R09: ffff8880ae620f8b R10: 0000000000000000 R11: 6c6c756e28202020 R12: dffffc0000000000 R13: ffffffff8c709bb8 R14: 0000000000000009 R15: 0000000000000000 FS: 00007f7930053700(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000004e9cf0 CR3: 000000008f8ef000 CR4: 00000000001506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 --- This report is generated by a bot. 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