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: 17252 Comm: syz-executor.3 Not tainted 5.11.0-rc2-next-20210108-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 b3 18 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:ffffc9001835fd00 EFLAGS: 00010207
RAX: dffffc0000000000 RBX: ffff888014310500 RCX: 0000000000000000
RDX: 000000000000000c RSI: ffffffff81c1aded RDI: 0000000000000064
RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffff8ebe68ef
R10: ffffffff840d236f R11: 0000000000000000 R12: ffff888014310508
R13: ffff888018c8e008 R14: ffff888070dbf028 R15: ffff888070db9648
FS:  0000000002625940(0000) GS:ffff8880b9f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b30322000 CR3: 000000002720c000 CR4: 00000000001526e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 tty_unregister_device drivers/tty/tty_io.c:3241 [inline]
 tty_unregister_device+0x112/0x1b0 drivers/tty/tty_io.c:3236
 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+0xe1/0x2a0 drivers/tty/tty_ldisc.c:809
 tty_release_struct+0x20/0xe0 drivers/tty/tty_io.c:1618
 tty_release+0xc70/0x1210 drivers/tty/tty_io.c:1789
 __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
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x417b71
Code: 75 14 b8 03 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 a4 1a 00 00 c3 48 83 ec 08 e8 0a fc ff ff 48 89 04 24 b8 03 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 53 fc ff ff 48 89 d0 48 83 c4 08 48 3d 01
RSP: 002b:00007ffe97f10680 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000004 RCX: 0000000000417b71
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000003
RBP: 0000000000000001 R08: 0000000000000138 R09: 000000007b2e213c
R10: 00007ffe97f10760 R11: 0000000000000293 R12: 000000000119ca00
R13: 000000000119ca00 R14: 00000000000003e8 R15: 000000000119bf8c
Modules linked in:
---[ end trace 206948a49b099a87 ]---
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 b3 18 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:ffffc9001835fd00 EFLAGS: 00010207
RAX: dffffc0000000000 RBX: ffff888014310500 RCX: 0000000000000000
RDX: 000000000000000c RSI: ffffffff81c1aded RDI: 0000000000000064
RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffff8ebe68ef
R10: ffffffff840d236f R11: 0000000000000000 R12: ffff888014310508
R13: ffff888018c8e008 R14: ffff888070dbf028 R15: ffff888070db9648
FS:  0000000002625940(0000) GS:ffff8880b9f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc31c301db8 CR3: 000000002720c000 CR4: 00000000001526e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400