general protection fault, probably for non-canonical address 0xdffffc000000000c: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000060-0x0000000000000067]
CPU: 1 PID: 26349 Comm: syz-executor.1 Not tainted 5.12.0-rc4-next-20210326-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:cdev_del+0x22/0x90 fs/char_dev.c:596
Code: b5 0f 1f 80 00 00 00 00 55 48 89 fd 48 83 ec 08 e8 c3 ab af ff 48 8d 7d 64 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 14 02 48 89 f8 83 e0 07 83 c0 03 38 d0 7c 04 84 d2 75 4f 48
RSP: 0018:ffffc90021ff7c60 EFLAGS: 00010207
RAX: dffffc0000000000 RBX: ffff88814298e700 RCX: 0000000000000000
RDX: 000000000000000c RSI: ffffffff81c47d0d RDI: 0000000000000064
RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffff8fae6937
R10: ffffffff841d051f R11: 0000000000000000 R12: ffff88814298e708
R13: ffff888142add008 R14: ffff8880b0fc6420 R15: ffff8880b0fc6278
FS:  0000000002399400(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b33828000 CR3: 00000000a3926000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 tty_unregister_device drivers/tty/tty_io.c:3342 [inline]
 tty_unregister_device+0x112/0x1b0 drivers/tty/tty_io.c:3337
 gsmld_detach_gsm drivers/tty/n_gsm.c:2409 [inline]
 gsmld_close+0xaa/0x260 drivers/tty/n_gsm.c:2475
 tty_ldisc_close+0x110/0x190 drivers/tty/tty_ldisc.c:488
 tty_ldisc_kill+0x94/0x150 drivers/tty/tty_ldisc.c:636
 tty_ldisc_hangup+0x30b/0x680 drivers/tty/tty_ldisc.c:756
 __tty_hangup.part.0+0x40a/0x870 drivers/tty/tty_io.c:639
 __tty_hangup drivers/tty/tty_io.c:595 [inline]
 tty_vhangup+0x1d/0x30 drivers/tty/tty_io.c:712
 pty_close+0x3ec/0x540 drivers/tty/pty.c:78
 tty_release+0x45e/0x1210 drivers/tty/tty_io.c:1778
 __fput+0x288/0x920 fs/file_table.c:280
 task_work_run+0xdd/0x1a0 kernel/task_work.c:143
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:174 [inline]
 exit_to_user_mode_prepare+0x249/0x250 kernel/entry/common.c:208
 __syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
 syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:301
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x41926b
Code: 0f 05 48 3d 00 f0 ff ff 77 45 c3 0f 1f 40 00 48 83 ec 18 89 7c 24 0c e8 63 fc ff ff 8b 7c 24 0c 41 89 c0 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 35 44 89 c7 89 44 24 0c e8 a1 fc ff ff 8b 44
RSP: 002b:00007ffd8a8930c0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000004 RCX: 000000000041926b
RDX: 0000000000000000 RSI: 0000001b33825e58 RDI: 0000000000000003
RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000001676
R10: 00000000e894f67a R11: 0000000000000293 R12: 000000000056c9e0
R13: 000000000056c9e0 R14: 000000000056bf60 R15: 000000000010b059
Modules linked in:
---[ end trace a966ed0439183ea0 ]---
RIP: 0010:cdev_del+0x22/0x90 fs/char_dev.c:596
Code: b5 0f 1f 80 00 00 00 00 55 48 89 fd 48 83 ec 08 e8 c3 ab af ff 48 8d 7d 64 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 14 02 48 89 f8 83 e0 07 83 c0 03 38 d0 7c 04 84 d2 75 4f 48
RSP: 0018:ffffc90021ff7c60 EFLAGS: 00010207
RAX: dffffc0000000000 RBX: ffff88814298e700 RCX: 0000000000000000
RDX: 000000000000000c RSI: ffffffff81c47d0d RDI: 0000000000000064
RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffff8fae6937
R10: ffffffff841d051f R11: 0000000000000000 R12: ffff88814298e708
R13: ffff888142add008 R14: ffff8880b0fc6420 R15: ffff8880b0fc6278
FS:  0000000002399400(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000056c000 CR3: 00000000a3926000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400