general protection fault, probably for non-canonical address 0xdffffc000000000c: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000060-0x0000000000000067]
CPU: 0 PID: 19572 Comm: syz-executor.1 Not tainted 5.11.0-rc6-syzkaller #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
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 63 54 b1 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:ffffc9002a367cd0 EFLAGS: 00010207
RAX: dffffc0000000000 RBX: ffff888041e0ff00 RCX: 0000000000000000
RDX: 000000000000000c RSI: ffffffff81c1698d RDI: 0000000000000064
RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffff8f86683f
R10: ffffffff840eee6f R11: 0000000000000000 R12: ffff888041e0ff08
R13: ffff888018fc8008 R14: ffff88800040f3d0 R15: ffff888020a61648
FS:  0000000000000000(0000) GS:ffff88802ca00000(0063) knlGS:00000000094b0380
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 00007ffd4d3c8ff0 CR3: 0000000015a79000 CR4: 0000000000150ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 tty_unregister_device drivers/tty/tty_io.c:3217 [inline]
 tty_unregister_device+0x112/0x1b0 drivers/tty/tty_io.c:3212
 gsmld_detach_gsm drivers/tty/n_gsm.c:2409 [inline]
 gsmld_close+0xaa/0x260 drivers/tty/n_gsm.c:2478
 tty_ldisc_close+0x110/0x190 drivers/tty/tty_ldisc.c:488
 tty_ldisc_kill+0x94/0x150 drivers/tty/tty_ldisc.c:636
 tty_ldisc_release+0x1ef/0x2a0 drivers/tty/tty_ldisc.c:809
 tty_release_struct+0x20/0xe0 drivers/tty/tty_io.c:1629
 tty_release+0xc70/0x1210 drivers/tty/tty_io.c:1800
 __fput+0x283/0x920 fs/file_table.c:280
 task_work_run+0xdd/0x190 kernel/task_work.c:140
 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:201
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x19/0x50 kernel/entry/common.c:302
 __do_fast_syscall_32+0x62/0x80 arch/x86/entry/common.c:142
 do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:164
 entry_SYSENTER_compat_after_hwframe+0x4d/0x5c
RIP: 0023:0xf7fdf549
Code: 03 74 c0 01 10 05 03 74 b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00
RSP: 002b:00000000fff3cba0 EFLAGS: 00000282 ORIG_RAX: 0000000000000006
RAX: 0000000000000000 RBX: 0000000000000003 RCX: 0000000000000002
RDX: 0000000000000000 RSI: 0000000008165000 RDI: 0000000000000003
RBP: 00000000ffffffff R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
Modules linked in:
Dumping ftrace buffer:
   (ftrace buffer empty)
---[ end trace 6995aa1da8f58295 ]---
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 63 54 b1 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:ffffc9002a367cd0 EFLAGS: 00010207
RAX: dffffc0000000000 RBX: ffff888041e0ff00 RCX: 0000000000000000
RDX: 000000000000000c RSI: ffffffff81c1698d RDI: 0000000000000064
RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffff8f86683f
R10: ffffffff840eee6f R11: 0000000000000000 R12: ffff888041e0ff08
R13: ffff888018fc8008 R14: ffff88800040f3d0 R15: ffff888020a61648
FS:  0000000000000000(0000) GS:ffff88802ca00000(0063) knlGS:00000000094b0380
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 00007f7c69575930 CR3: 0000000015a79000 CR4: 0000000000150ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400