BUG: kernel NULL pointer dereference, address: 0000000000000000 #PF: supervisor instruction fetch in kernel mode #PF: error_code(0x0010) - not-present page PGD 26ce4067 P4D 26ce4067 PUD 7ac3b067 PMD 0 Oops: 0010 [#1] PREEMPT SMP KASAN CPU: 0 PID: 5363 Comm: kworker/u4:15 Not tainted 6.0.0-rc3-syzkaller-00215-g0b3acd1cc022 #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:ffffc90004f5fbb8 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffff888074a5f000 RCX: 0000000000000003 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff888074a5f000 RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000004 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000725 R13: 0000000000000000 R14: ffff888031dd00fb R15: dffffc0000000000 FS: 0000000000000000(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffffffffd6 CR3: 00000000776f8000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: 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 Modules linked in: CR2: 0000000000000000 ---[ end trace 0000000000000000 ]--- RIP: 0010:0x0 Code: Unable to access opcode bytes at RIP 0xffffffffffffffd6. RSP: 0018:ffffc90004f5fbb8 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffff888074a5f000 RCX: 0000000000000003 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff888074a5f000 RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000004 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000725 R13: 0000000000000000 R14: ffff888031dd00fb R15: dffffc0000000000 FS: 0000000000000000(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffffffffd6 CR3: 00000000776f8000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400