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: 18812 Comm: syz-executor.4 Not tainted 5.8.0-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 63 f9 b4 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:ffffc90017ddfac8 EFLAGS: 00010207
RAX: dffffc0000000000 RBX: ffff8880a1866600 RCX: ffffc900112d0000
RDX: 000000000000000c RSI: ffffffff81bec32d RDI: 0000000000000064
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880a1866608
R13: ffff8880a193d008 R14: ffff88804d09c028 R15: ffff888091f0d650
FS:  00007ff223463700(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000043da30 CR3: 000000004ca9a000 CR4: 00000000001406f0
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_release+0xe1/0x2a0 drivers/tty/tty_ldisc.c:809
 tty_release_struct+0x20/0xe0 drivers/tty/tty_io.c:1614
 tty_release+0xc67/0xf60 drivers/tty/tty_io.c:1785
 __fput+0x33c/0x880 fs/file_table.c:281
 task_work_run+0xdd/0x190 kernel/task_work.c:135
 get_signal+0xd6c/0x1ee0 kernel/signal.c:2547
 do_signal+0x82/0x2520 arch/x86/kernel/signal.c:810
 exit_to_usermode_loop arch/x86/entry/common.c:235 [inline]
 __prepare_exit_to_usermode+0x156/0x1f0 arch/x86/entry/common.c:269
 do_syscall_64+0x6c/0xe0 arch/x86/entry/common.c:393
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45c1f9
Code: Bad RIP value.
RSP: 002b:00007ff223462c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: 0000000000000000 RBX: 0000000000017f40 RCX: 000000000045c1f9
RDX: 00000000200000c0 RSI: 0000000000005423 RDI: 0000000000000004
RBP: 00007ff223462ca0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000009
R13: 00007fffd3ca5ccf R14: 00007ff2234639c0 R15: 000000000078bf0c
Modules linked in:
---[ end trace f184fce6c4abddf8 ]---
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 f9 b4 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:ffffc90017ddfac8 EFLAGS: 00010207
RAX: dffffc0000000000 RBX: ffff8880a1866600 RCX: ffffc900112d0000
RDX: 000000000000000c RSI: ffffffff81bec32d RDI: 0000000000000064
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880a1866608
R13: ffff8880a193d008 R14: ffff88804d09c028 R15: ffff888091f0d650
FS:  00007ff223463700(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000043da30 CR3: 000000004ca9a000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400