BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor instruction fetch in kernel mode
#PF: error_code(0x0010) - not-present page
PGD 4bdeb067 P4D 4bdeb067 PUD 0 
Oops: 0010 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 3744 Comm: kworker/u4:6 Not tainted 6.0.0-rc2-syzkaller-00191-g3e5c673f0d75 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022
Workqueue: events_unbound flush_to_ldisc
RIP: 0010:0x0
Code: Unable to access opcode bytes at RIP 0xffffffffffffffd6.
RSP: 0018:ffffc900043a7ab0 EFLAGS: 00010246
RAX: 1ffff11004d78400 RBX: 0000000000000000 RCX: dffffc0000000000
RDX: ffff888026bc221f RSI: 000000000000005e RDI: ffff8880477b3000
RBP: 0000000000000000 R08: 0000000000000005 R09: ffffffff84aeb70b
R10: 0000000000000005 R11: ffff88802606bb00 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 000000002f799000 CR4: 00000000003506e0
Call Trace:
 <TASK>
 gsmld_receive_buf+0x1dc/0x350 drivers/tty/n_gsm.c:2861
 tty_ldisc_receive_buf+0x128/0x170 drivers/tty/tty_buffer.c:461
 tty_port_default_receive_buf+0x6a/0x90 drivers/tty/tty_port.c:39
 receive_buf drivers/tty/tty_buffer.c:511 [inline]
 flush_to_ldisc+0x2e8/0x850 drivers/tty/tty_buffer.c:561
 process_one_work+0x81c/0xd10 kernel/workqueue.c:2289
 worker_thread+0xb14/0x1330 kernel/workqueue.c:2436
 kthread+0x266/0x300 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30
 </TASK>
Modules linked in:
CR2: 0000000000000000
---[ end trace 0000000000000000 ]---
RIP: 0010:0x0
Code: Unable to access opcode bytes at RIP 0xffffffffffffffd6.
RSP: 0018:ffffc900043a7ab0 EFLAGS: 00010246
RAX: 1ffff11004d78400 RBX: 0000000000000000 RCX: dffffc0000000000
RDX: ffff888026bc221f RSI: 000000000000005e RDI: ffff8880477b3000
RBP: 0000000000000000 R08: 0000000000000005 R09: ffffffff84aeb70b
R10: 0000000000000005 R11: ffff88802606bb00 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 000000002f799000 CR4: 00000000003506e0