@@ -257,8 +257,13 @@ static void evdev_pass_values(struct evdev_client *client,
event.input_event_sec = ts.tv_sec;
event.input_event_usec = ts.tv_nsec / NSEC_PER_USEC;
- /* Interrupts are disabled, just acquire the lock. */
- spin_lock(&client->buffer_lock);
+ /*
+ * Disable lockdep chain connecting with subclass based on fasync
+ * to suppress lockdep report. No further locking for NULL fasync
+ * (keybord_tasklet injecting input events).
+ * Interrupts are disabled, just acquire the lock.
+ */
+ spin_lock_nested(&client->buffer_lock, !client->fasync);
for (v = vals; v != vals + count; v++) {
if (__evdev_is_filtered(client, v->type, v->code))
Lockdep connects soft irq (keyboard tasklet injecting led events) and vfs started (lease break) locking chains. In the test scenario the chains do not connect due to event type/code and client->fasync. commit 45a3e24f65e9 ("Linux 6.4-rc7") Backtrace ===================================================== WARNING: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected 5.10.0-syzkaller #0 Not tainted ----------------------------------------------------- syz-executor175/2640 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire: ffffffff8720b458 (tasklist_lock){.+.+}-{2:2}, at: send_sigio+0xdc/0x340 and this task is already holding: ffff88800bc0e978 (&f->f_owner.lock){....}-{2:2}, at: send_sigio+0x31/0x340 which would create a new lock dependency: (&f->f_owner.lock){....}-{2:2} -> (tasklist_lock){.+.+}-{2:2} but this new dependency connects a SOFTIRQ-irq-safe lock: (&client->buffer_lock){..-.}-{2:2} ... which became SOFTIRQ-irq-safe at: lock_acquire+0x197/0x480 _raw_spin_lock+0x2a/0x40 evdev_pass_values+0xef/0xaf0 evdev_events+0x1ba/0x2f0 input_pass_values+0x87e/0x1200 input_handle_event+0xc17/0x1500 input_inject_event+0x1eb/0x2f0 kbd_update_leds_helper+0xfd/0x130 input_handler_for_each_handle+0xdc/0x1a0 kbd_bh+0x180/0x250 tasklet_action_common+0x2e1/0x3d0 tasklet_action+0x1d/0x20 __do_softirq+0x3e6/0x94e run_ksoftirqd+0x96/0xf0 smpboot_thread_fn+0x557/0x900 kthread+0x374/0x3f0 ret_from_fork+0x3a/0x50 to a SOFTIRQ-irq-unsafe lock: (tasklist_lock){.+.+}-{2:2} ... which became SOFTIRQ-irq-unsafe at: ... lock_acquire+0x197/0x480 _raw_read_lock+0x32/0x50 do_wait+0x356/0xc80 kernel_wait+0xe5/0x240 call_usermodehelper_exec_work+0xb7/0x220 process_one_work+0x857/0xfd0 worker_thread+0xafa/0x1550 kthread+0x374/0x3f0 ret_from_fork+0x3a/0x50 other info that might help us debug this: Chain exists of: &client->buffer_lock --> &f->f_owner.lock --> tasklist_lock Possible interrupt unsafe locking scenario: CPU0 CPU1 ---- ---- lock(tasklist_lock); local_irq_disable(); lock(&client->buffer_lock); lock(&f->f_owner.lock); <Interrupt> lock(&client->buffer_lock); *** DEADLOCK *** 5 locks held by syz-executor175/2640: #0: ffffffff879b7bf0 (file_rwsem){.+.+}-{0:0}, at: __break_lease+0x186/0x1300 #1: ffff88800f2d2dd8 (&ctx->flc_lock){+.+.}-{2:2}, at: __break_lease+0x193/0x1300 #2: ffffffff8784ba80 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x9/0x40 #3: ffff88800ea3d9f0 (&new->fa_lock){....}-{2:2}, at: kill_fasync+0x15f/0x480 #4: ffff88800bc0e978 (&f->f_owner.lock){....}-{2:2}, at: send_sigio+0x31/0x340 the dependencies between SOFTIRQ-irq-safe lock and the holding lock: -> (&client->buffer_lock){..-.}-{2:2} { IN-SOFTIRQ-W at: lock_acquire+0x197/0x480 _raw_spin_lock+0x2a/0x40 evdev_pass_values+0xef/0xaf0 evdev_events+0x1ba/0x2f0 input_pass_values+0x87e/0x1200 input_handle_event+0xc17/0x1500 input_inject_event+0x1eb/0x2f0 kbd_update_leds_helper+0xfd/0x130 input_handler_for_each_handle+0xdc/0x1a0 kbd_bh+0x180/0x250 tasklet_action_common+0x2e1/0x3d0 tasklet_action+0x1d/0x20 __do_softirq+0x3e6/0x94e run_ksoftirqd+0x96/0xf0 smpboot_thread_fn+0x557/0x900 kthread+0x374/0x3f0 ret_from_fork+0x3a/0x50 INITIAL USE at: lock_acquire+0x197/0x480 _raw_spin_lock+0x2a/0x40 evdev_pass_values+0xef/0xaf0 evdev_events+0x1ba/0x2f0 input_pass_values+0x87e/0x1200 input_handle_event+0xc17/0x1500 input_inject_event+0x1eb/0x2f0 evdev_write+0x37b/0x580 vfs_write+0x287/0xc90 ksys_write+0x17e/0x2a0 __x64_sys_write+0x7b/0x90 do_syscall_64+0x4f/0x60 entry_SYSCALL_64_after_hwframe+0x61/0xc6 } ... key at: [<ffffffff895f5640>] evdev_open.__key.17+0x0/0x20 -> (&new->fa_lock){....}-{2:2} { INITIAL READ USE at: lock_acquire+0x197/0x480 _raw_read_lock_irqsave+0xb8/0x100 kill_fasync+0x15f/0x480 evdev_pass_values+0x5b9/0xaf0 evdev_events+0x1ba/0x2f0 input_pass_values+0x87e/0x1200 input_handle_event+0xc17/0x1500 input_inject_event+0x1eb/0x2f0 evdev_write+0x37b/0x580 vfs_write+0x287/0xc90 ksys_write+0x17e/0x2a0 __x64_sys_write+0x7b/0x90 do_syscall_64+0x4f/0x60 entry_SYSCALL_64_after_hwframe+0x61/0xc6 } ... key at: [<ffffffff8943f5e0>] fasync_insert_entry.__key+0x0/0x20 ... acquired at: lock_acquire+0x197/0x480 _raw_read_lock_irqsave+0xb8/0x100 kill_fasync+0x15f/0x480 evdev_pass_values+0x5b9/0xaf0 evdev_events+0x1ba/0x2f0 input_pass_values+0x87e/0x1200 input_handle_event+0xc17/0x1500 input_inject_event+0x1eb/0x2f0 evdev_write+0x37b/0x580 vfs_write+0x287/0xc90 ksys_write+0x17e/0x2a0 __x64_sys_write+0x7b/0x90 do_syscall_64+0x4f/0x60 entry_SYSCALL_64_after_hwframe+0x61/0xc6 -> (&f->f_owner.lock){....}-{2:2} { INITIAL USE at: lock_acquire+0x197/0x480 _raw_write_lock_irq+0xab/0xf0 f_modown+0x3b/0x350 do_fcntl+0x139b/0x1750 __se_sys_fcntl+0xe3/0x1c0 __x64_sys_fcntl+0x7b/0x90 do_syscall_64+0x4f/0x60 entry_SYSCALL_64_after_hwframe+0x61/0xc6 INITIAL READ USE at: lock_acquire+0x197/0x480 _raw_read_lock_irqsave+0xb8/0x100 send_sigio+0x31/0x340 kill_fasync+0x1fb/0x480 evdev_pass_values+0x5b9/0xaf0 evdev_events+0x1ba/0x2f0 input_pass_values+0x87e/0x1200 input_handle_event+0xc17/0x1500 input_inject_event+0x1eb/0x2f0 evdev_write+0x37b/0x580 vfs_write+0x287/0xc90 ksys_write+0x17e/0x2a0 __x64_sys_write+0x7b/0x90 do_syscall_64+0x4f/0x60 entry_SYSCALL_64_after_hwframe+0x61/0xc6 } ... key at: [<ffffffff8943e960>] __alloc_file.__key+0x0/0x10 ... acquired at: lock_acquire+0x197/0x480 _raw_read_lock_irqsave+0xb8/0x100 send_sigio+0x31/0x340 kill_fasync+0x1fb/0x480 evdev_pass_values+0x5b9/0xaf0 evdev_events+0x1ba/0x2f0 input_pass_values+0x87e/0x1200 input_handle_event+0xc17/0x1500 input_inject_event+0x1eb/0x2f0 evdev_write+0x37b/0x580 vfs_write+0x287/0xc90 ksys_write+0x17e/0x2a0 __x64_sys_write+0x7b/0x90 do_syscall_64+0x4f/0x60 entry_SYSCALL_64_after_hwframe+0x61/0xc6 the dependencies between the lock to be acquired and SOFTIRQ-irq-unsafe lock: -> (tasklist_lock){.+.+}-{2:2} { HARDIRQ-ON-R at: lock_acquire+0x197/0x480 _raw_read_lock+0x32/0x50 do_wait+0x356/0xc80 kernel_wait+0xe5/0x240 call_usermodehelper_exec_work+0xb7/0x220 process_one_work+0x857/0xfd0 worker_thread+0xafa/0x1550 kthread+0x374/0x3f0 ret_from_fork+0x3a/0x50 SOFTIRQ-ON-R at: lock_acquire+0x197/0x480 _raw_read_lock+0x32/0x50 do_wait+0x356/0xc80 kernel_wait+0xe5/0x240 call_usermodehelper_exec_work+0xb7/0x220 process_one_work+0x857/0xfd0 worker_thread+0xafa/0x1550 kthread+0x374/0x3f0 ret_from_fork+0x3a/0x50 INITIAL USE at: lock_acquire+0x197/0x480 _raw_write_lock_irq+0xab/0xf0 copy_process+0x2192/0x3880 kernel_clone+0x220/0x7a0 kernel_thread+0x147/0x1c0 rest_init+0x24/0x300 arch_call_rest_init+0xe/0x11 start_kernel+0x469/0x512 x86_64_start_reservations+0x2a/0x2d x86_64_start_kernel+0x60/0x64 secondary_startup_64_no_verify+0xac/0xbb INITIAL READ USE at: lock_acquire+0x197/0x480 _raw_read_lock+0x32/0x50 do_wait+0x356/0xc80 kernel_wait+0xe5/0x240 call_usermodehelper_exec_work+0xb7/0x220 process_one_work+0x857/0xfd0 worker_thread+0xafa/0x1550 kthread+0x374/0x3f0 ret_from_fork+0x3a/0x50 } ... key at: [<ffffffff8720b458>] tasklist_lock+0x18/0x40 ... acquired at: lock_acquire+0x197/0x480 _raw_read_lock+0x32/0x50 send_sigio+0xdc/0x340 kill_fasync+0x1fb/0x480 lease_break_callback+0x26/0x30 __break_lease+0x4d1/0x1300 do_dentry_open+0x6ac/0xf40 vfs_open+0x73/0x80 path_openat+0x26c5/0x3290 do_filp_open+0x20b/0x450 do_sys_openat2+0x124/0x460 __x64_sys_open+0x221/0x270 do_syscall_64+0x4f/0x60 entry_SYSCALL_64_after_hwframe+0x61/0xc6 stack backtrace: CPU: 2 PID: 2640 Comm: syz-executor175 Not tainted 5.10.0-syzkaller #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014 Call Trace: dump_stack+0x183/0x226 validate_chain+0x4cca/0x5870 __lock_acquire+0x12fd/0x20d0 lock_acquire+0x197/0x480 _raw_read_lock+0x32/0x50 send_sigio+0xdc/0x340 kill_fasync+0x1fb/0x480 lease_break_callback+0x26/0x30 __break_lease+0x4d1/0x1300 do_dentry_open+0x6ac/0xf40 vfs_open+0x73/0x80 path_openat+0x26c5/0x3290 do_filp_open+0x20b/0x450 do_sys_openat2+0x124/0x460 __x64_sys_open+0x221/0x270 do_syscall_64+0x4f/0x60 entry_SYSCALL_64_after_hwframe+0x61/0xc6 RIP: 0033:0x7f65eb366509 Code: 28 c3 e8 1a 15 00 00 66 2e 0f 1f 84 00 00 00 00 00 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 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fffac3b94b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000002 RAX: ffffffffffffffda RBX: 00007f65eb3d3ed0 RCX: 00007f65eb366509 RDX: 0000000000000000 RSI: 0000000000004c01 RDI: 0000000020000240 RBP: 00007fffac3b94c8 R08: 00007f65eb3d3e40 R09: 00007f65eb3d3e40 R10: 00007f65eb3d3e40 R11: 0000000000000246 R12: 00007fffac3b94d0 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 Signed-off-by: Wojciech Gładysz <wojciech.gladysz@infogain.com> --- drivers/input/evdev.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)