BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor instruction fetch in kernel mode
#PF: error_code(0x0010) - not-present page
PGD 7ca34067 P4D 7ca34067 PUD 0 
Oops: 0010 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 6554 Comm: kworker/u4:19 Not tainted 6.0.0-rc2-syzkaller-00248-ge022620b5d05 #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:ffffc90005b8fbb8 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff888031c58000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 00000000000000e8 RDI: ffff888031c58000
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000004
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000001
R13: 0000000000000000 R14: ffff888020d50820 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 00000000307c1000 CR4: 0000000000350ee0
Call Trace:
 <TASK>
 gsmld_receive_buf+0x1c2/0x2f0 drivers/tty/n_gsm.c:2861
 tty_ldisc_receive_buf+0x14d/0x190 drivers/tty/tty_buffer.c:461
 tty_port_default_receive_buf+0x6e/0xa0 drivers/tty/tty_port.c:39
 receive_buf drivers/tty/tty_buffer.c:511 [inline]
 flush_to_ldisc+0x219/0x6c0 drivers/tty/tty_buffer.c:561
 process_one_work+0x991/0x1610 kernel/workqueue.c:2289
 worker_thread+0x665/0x1080 kernel/workqueue.c:2436
 kthread+0x2e4/0x3a0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
 </TASK>
Modules linked in:
CR2: 0000000000000000
---[ end trace 0000000000000000 ]---
RIP: 0010:0x0
Code: Unable to access opcode bytes at RIP 0xffffffffffffffd6.
RSP: 0018:ffffc90005b8fbb8 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff888031c58000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 00000000000000e8 RDI: ffff888031c58000
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000004
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000001
R13: 0000000000000000 R14: ffff888020d50820 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 00000000307c1000 CR4: 0000000000350ee0