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: 13772 Comm: syz-executor.4 Not tainted 5.7.0-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 68 b5 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:ffffc9000ad6fc30 EFLAGS: 00010207
RAX: dffffc0000000000 RBX: ffff8880a206e600 RCX: ffffffff83e78bbe
RDX: 000000000000000c RSI: ffffffff81be662d RDI: 0000000000000064
RBP: 0000000000000000 R08: ffff8880458a8100 R09: 0000000000000001
R10: ffffffff8c347a27 R11: fffffbfff1868f44 R12: 0000000000000008
R13: ffff8880a27ac008 R14: ffff8880a0014278 R15: ffff8880a7219040
FS:  0000000000000000(0000) GS:ffff8880ae700000(0063) knlGS:0000000008a04900
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 0000000031423000 CR3: 000000004ab4a000 CR4: 00000000001426e0
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+0x10d/0x1a0 drivers/tty/tty_io.c:3188
 gsmld_detach_gsm drivers/tty/n_gsm.c:2418 [inline]
 gsmld_close+0xb3/0x1f0 drivers/tty/n_gsm.c:2487
 tty_ldisc_close.isra.0+0x110/0x190 drivers/tty/tty_ldisc.c:489
 tty_ldisc_kill+0x94/0x150 drivers/tty/tty_ldisc.c:637
 tty_ldisc_hangup+0x2d0/0x630 drivers/tty/tty_ldisc.c:756
 __tty_hangup.part.0+0x2ef/0x730 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 drivers/tty/pty.c:79 [inline]
 pty_close+0x3f5/0x550 drivers/tty/pty.c:46
 tty_release+0x3b9/0xe90 drivers/tty/tty_io.c:1679
 __fput+0x33e/0x880 fs/file_table.c:281
 task_work_run+0xf4/0x1b0 kernel/task_work.c:123
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop+0x2fa/0x360 arch/x86/entry/common.c:165
 prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:279 [inline]
 do_syscall_32_irqs_on arch/x86/entry/common.c:340 [inline]
 do_fast_syscall_32+0xbef/0xe90 arch/x86/entry/common.c:396
 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139
Modules linked in:
---[ end trace 8a957a31736a8e8a ]---
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 68 b5 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:ffffc9000ad6fc30 EFLAGS: 00010207
RAX: dffffc0000000000 RBX: ffff8880a206e600 RCX: ffffffff83e78bbe
RDX: 000000000000000c RSI: ffffffff81be662d RDI: 0000000000000064
RBP: 0000000000000000 R08: ffff8880458a8100 R09: 0000000000000001
R10: ffffffff8c347a27 R11: fffffbfff1868f44 R12: 0000000000000008
R13: ffff8880a27ac008 R14: ffff8880a0014278 R15: ffff8880a7219040
FS:  0000000000000000(0000) GS:ffff8880ae700000(0063) knlGS:0000000008a04900
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 00007fe8b2c16000 CR3: 000000004ab4a000 CR4: 00000000001426e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400