BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor instruction fetch in kernel mode
#PF: error_code(0x0010) - not-present page
PGD 761ed067 P4D 761ed067 PUD 22ac7067 PMD 0 
Oops: 0010 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 7496 Comm: syz-executor.3 Not tainted 6.0.0-rc3-syzkaller-00215-g0b3acd1cc022 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022
RIP: 0010:0x0
Code: Unable to access opcode bytes at RIP 0xffffffffffffffd6.
RSP: 0018:ffffc900034a7d90 EFLAGS: 00010297
RAX: 1ffff92000694f01 RBX: 0000000000000000 RCX: 00000000034a7e00
RDX: ffffc900034a7e40 RSI: 0000000000000008 RDI: ffff88803926f000
RBP: 0000000000000000 R08: 0000000000000005 R09: ffffffff84aec39b
R10: 0000000000000005 R11: ffff88803be35880 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: ffffc900034a7e51
FS:  00007f60850cd700(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 00000000263e4000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 gsmld_receive_buf+0x1dc/0x350 drivers/tty/n_gsm.c:2861
 tiocsti+0x237/0x2f0 drivers/tty/tty_io.c:2293
 tty_ioctl+0x3a8/0xc60 drivers/tty/tty_io.c:2692
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0xfb/0x170 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f6083e89279
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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f60850cd168 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f6083f9bf80 RCX: 00007f6083e89279
RDX: 00000000200000c0 RSI: 0000000000005412 RDI: 0000000000000003
RBP: 00007f6083ee32e9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffde667063f R14: 00007f60850cd300 R15: 0000000000022000
 </TASK>
Modules linked in:
CR2: 0000000000000000
---[ end trace 0000000000000000 ]---
RIP: 0010:0x0
Code: Unable to access opcode bytes at RIP 0xffffffffffffffd6.
RSP: 0018:ffffc900034a7d90 EFLAGS: 00010297
RAX: 1ffff92000694f01 RBX: 0000000000000000 RCX: 00000000034a7e00
RDX: ffffc900034a7e40 RSI: 0000000000000008 RDI: ffff88803926f000
RBP: 0000000000000000 R08: 0000000000000005 R09: ffffffff84aec39b
R10: 0000000000000005 R11: ffff88803be35880 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: ffffc900034a7e51
FS:  00007f60850cd700(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 00000000263e4000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400