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: 10127 Comm: syz-executor.5 Not tainted 5.9.0-rc6-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 d3 41 b3 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:ffffc90018e17c48 EFLAGS: 00010207
RAX: dffffc0000000000 RBX: ffff8882185d0400 RCX: ffffffff841165ff
RDX: 000000000000000c RSI: ffffffff81c2fc6d RDI: 0000000000000064
RBP: 0000000000000000 R08: 0000000000000001 R09: ffffffff8d0b7a67
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8882185d0408
R13: ffff8882185d7008 R14: ffff88809493a420 R15: ffff88809493a278
FS:  0000000002259940(0000) GS:ffff8880ae500000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fff549a7887 CR3: 00000000a7f4e000 CR4: 00000000001526e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 tty_unregister_device drivers/tty/tty_io.c:3193 [inline]
 tty_unregister_device+0x112/0x1b0 drivers/tty/tty_io.c:3188
 gsmld_detach_gsm drivers/tty/n_gsm.c:2411 [inline]
 gsmld_close+0xaa/0x260 drivers/tty/n_gsm.c:2480
 tty_ldisc_close+0x110/0x190 drivers/tty/tty_ldisc.c:489
 tty_ldisc_kill+0x94/0x150 drivers/tty/tty_ldisc.c:637
 tty_ldisc_hangup+0x30b/0x680 drivers/tty/tty_ldisc.c:756
 __tty_hangup.part.0+0x403/0x870 drivers/tty/tty_io.c:625
 __tty_hangup drivers/tty/tty_io.c:575 [inline]
 tty_vhangup+0x1d/0x30 drivers/tty/tty_io.c:698
 pty_close+0x3f5/0x550 drivers/tty/pty.c:79
 tty_release+0x455/0xf60 drivers/tty/tty_io.c:1679
 __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:165 [inline]
 exit_to_user_mode_prepare+0x1e1/0x200 kernel/entry/common.c:192
 syscall_exit_to_user_mode+0x7e/0x2e0 kernel/entry/common.c:267
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x417901
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:000000000169fbe0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000005 RCX: 0000000000417901
RDX: 0000000000000000 RSI: 0000000000001684 RDI: 0000000000000004
RBP: 0000000000000001 R08: 000000007435d684 R09: 000000007435d688
R10: 000000000169fcd0 R11: 0000000000000293 R12: 0000000001190ee8
R13: 00000000001ccfe1 R14: ffffffffffffffff R15: 000000000118cf4c
Modules linked in:
---[ end trace 6ba17187813bf7da ]---
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 d3 41 b3 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:ffffc90018e17c48 EFLAGS: 00010207
RAX: dffffc0000000000 RBX: ffff8882185d0400 RCX: ffffffff841165ff
RDX: 000000000000000c RSI: ffffffff81c2fc6d RDI: 0000000000000064
RBP: 0000000000000000 R08: 0000000000000001 R09: ffffffff8d0b7a67
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8882185d0408
R13: ffff8882185d7008 R14: ffff88809493a420 R15: ffff88809493a278
FS:  0000000002259940(0000) GS:ffff8880ae500000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fd835bd3000 CR3: 00000000a7f4e000 CR4: 00000000001526e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400