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: 25583 Comm: syz-executor.0 Not tainted 5.12.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:cdev_del+0x21/0x90 fs/char_dev.c:596
Code: 84 00 00 00 00 00 0f 1f 00 55 41 56 53 48 89 fb 49 be 00 00 00 00 00 fc ff df e8 ba 18 b1 ff 48 8d 7b 60 48 89 f8 48 c1 e8 03 <42> 8a 04 30 84 c0 75 33 8b 6b 60 48 8d 7b 64 48 89 f8 48 c1 e8 03
RSP: 0018:ffffc900165efa58 EFLAGS: 00010206
RAX: 000000000000000c RBX: 0000000000000000 RCX: 0000000000040000
RDX: ffffc90001a31000 RSI: 000000000003ffff RDI: 0000000000000060
RBP: 0000000000000208 R08: ffffffff8434919c R09: fffffbfff1f296d9
R10: fffffbfff1f296d9 R11: 0000000000000000 R12: ffff888011abae08
R13: dffffc0000000000 R14: dffffc0000000000 R15: 1ffff110023575c1
FS:  00007f92eb44d700(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ff20ce6c718 CR3: 0000000091ea8000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 tty_unregister_device+0xed/0x170 drivers/tty/tty_io.c:3343
 gsmld_detach_gsm drivers/tty/n_gsm.c:2409 [inline]
 gsmld_close+0xa0/0x1e0 drivers/tty/n_gsm.c:2478
 tty_ldisc_kill drivers/tty/tty_ldisc.c:636 [inline]
 tty_ldisc_release+0x220/0x580 drivers/tty/tty_ldisc.c:809
 tty_release_struct+0x27/0xd0 drivers/tty/tty_io.c:1714
 tty_release+0xc5f/0xef0 drivers/tty/tty_io.c:1885
 __fput+0x352/0x7b0 fs/file_table.c:280
 task_work_run+0x146/0x1c0 kernel/task_work.c:140
 get_signal+0x1e47/0x1ef0 kernel/signal.c:2558
 arch_do_signal_or_restart+0x41/0x620 arch/x86/kernel/signal.c:789
 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+0xac/0x1e0 kernel/entry/common.c:208
 __syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
 syscall_exit_to_user_mode+0x26/0x70 kernel/entry/common.c:301
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x466459
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f92eb44d188 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: 0000000000000000 RBX: 000000000056bf60 RCX: 0000000000466459
RDX: 0000000020000040 RSI: 0000000000005423 RDI: 0000000000000003
RBP: 00007f92eb44d1d0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007fff6c0fbb2f R14: 00007f92eb44d300 R15: 0000000000022000
Modules linked in:
---[ end trace ba5669ec11b8b69c ]---
RIP: 0010:cdev_del+0x21/0x90 fs/char_dev.c:596
Code: 84 00 00 00 00 00 0f 1f 00 55 41 56 53 48 89 fb 49 be 00 00 00 00 00 fc ff df e8 ba 18 b1 ff 48 8d 7b 60 48 89 f8 48 c1 e8 03 <42> 8a 04 30 84 c0 75 33 8b 6b 60 48 8d 7b 64 48 89 f8 48 c1 e8 03
RSP: 0018:ffffc900165efa58 EFLAGS: 00010206
RAX: 000000000000000c RBX: 0000000000000000 RCX: 0000000000040000
RDX: ffffc90001a31000 RSI: 000000000003ffff RDI: 0000000000000060
RBP: 0000000000000208 R08: ffffffff8434919c R09: fffffbfff1f296d9
R10: fffffbfff1f296d9 R11: 0000000000000000 R12: ffff888011abae08
R13: dffffc0000000000 R14: dffffc0000000000 R15: 1ffff110023575c1
FS:  00007f92eb44d700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000543038 CR3: 0000000091ea8000 CR4: 00000000001506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400