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: 31301 Comm: syz-executor.5 Not tainted 5.11.0-rc1-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 93 d6 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:ffffc9000c61f970 EFLAGS: 00010207
RAX: dffffc0000000000 RBX: ffff888143e98e00 RCX: 0000000000000000
RDX: 000000000000000c RSI: ffffffff81c0a15d RDI: 0000000000000064
RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffff8ebe98a7
R10: ffffffff840c819f R11: 0000000000000000 R12: ffff888143e98e08
R13: ffff888143eed008 R14: ffff88802ad26028 R15: ffff8880264ef648
FS:  0000000000000000(0000) GS:ffff8880b9f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000749138 CR3: 0000000068c4d000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 tty_unregister_device drivers/tty/tty_io.c:3200 [inline]
 tty_unregister_device+0x112/0x1b0 drivers/tty/tty_io.c:3195
 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
 exit_task_work include/linux/task_work.h:30 [inline]
 do_exit+0xc5c/0x2ae0 kernel/exit.c:825
 do_group_exit+0x125/0x310 kernel/exit.c:922
 get_signal+0x3ec/0x2010 kernel/signal.c:2770
 arch_do_signal_or_restart+0x2a8/0x1eb0 arch/x86/kernel/signal.c:811
 handle_signal_work kernel/entry/common.c:147 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:171 [inline]
 exit_to_user_mode_prepare+0x148/0x250 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: 0033:0x45e219
Code: Unable to access opcode bytes at RIP 0x45e1ef.
RSP: 002b:00007fc3d0f6cc68 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: 0000000000000000 RBX: 0000000000000004 RCX: 000000000045e219
RDX: 0000000020000000 RSI: 0000000000005423 RDI: 0000000000000003
RBP: 00007fc3d0f6cca0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000009
R13: 00007ffdbfaee95f R14: 00007fc3d0f6d9c0 R15: 000000000119bf8c
Modules linked in:
---[ end trace ad81dd02bb9476f5 ]---
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 93 d6 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:ffffc9000c61f970 EFLAGS: 00010207
RAX: dffffc0000000000 RBX: ffff888143e98e00 RCX: 0000000000000000
RDX: 000000000000000c RSI: ffffffff81c0a15d RDI: 0000000000000064
RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffff8ebe98a7
R10: ffffffff840c819f R11: 0000000000000000 R12: ffff888143e98e08
R13: ffff888143eed008 R14: ffff88802ad26028 R15: ffff8880264ef648
FS:  0000000000000000(0000) GS:ffff8880b9f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000749138 CR3: 000000001928d000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400