RBP: 00007f36a714e1d0 R08: 0000000000000000 R09: 0000000000000000 kasan: CONFIG_KASAN_INLINE enabled R10: 00000000200000c0 R11: 0000000000000246 R12: 0000000000000001 R13: 00007ffcbafb2f6f R14: 00007f36a714e300 R15: 0000000000022000 kasan: GPF could be caused by NULL-ptr deref or user memory access general protection fault: 0000 [#1] PREEMPT SMP KASAN Modules linked in: CPU: 0 PID: 23729 Comm: syz-executor.1 Not tainted 4.14.307-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023 task: ffff8880a32aa040 task.stack: ffff88809e580000 RIP: 0010:cdev_del+0x22/0x90 fs/char_dev.c:602 RSP: 0018:ffff88809e587ca0 EFLAGS: 00010207 RAX: dffffc0000000000 RBX: ffff8880b0b6dc00 RCX: 0000000000000000 RDX: 000000000000000c RSI: ffff8880a32aa8c8 RDI: 0000000000000064 RBP: 0000000000000000 R08: ffffffff8b9c6380 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880b0b6dc08 R13: ffff8880af031308 R14: ffff8880b2dd1840 R15: ffff8880a53faed8 FS: 00005555555dd400(0000) GS:ffff8880ba400000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007facc659a000 CR3: 00000000b3829000 CR4: 00000000003406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: tty_unregister_device drivers/tty/tty_io.c:3046 [inline] tty_unregister_device+0x101/0x1a0 drivers/tty/tty_io.c:3041 gsmld_detach_gsm drivers/tty/n_gsm.c:2361 [inline] gsmld_close+0xaa/0x1f0 drivers/tty/n_gsm.c:2430 tty_ldisc_close+0x8c/0xc0 drivers/tty/tty_ldisc.c:505 tty_ldisc_kill drivers/tty/tty_ldisc.c:651 [inline] tty_ldisc_release+0xe8/0x400 drivers/tty/tty_ldisc.c:818 tty_release_struct+0x20/0xe0 drivers/tty/tty_io.c:1603 tty_release+0xb3f/0x10d0 drivers/tty/tty_io.c:1776 __fput+0x25f/0x7a0 fs/file_table.c:210 task_work_run+0x11f/0x190 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:191 [inline] exit_to_usermode_loop+0x1ad/0x200 arch/x86/entry/common.c:164 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline] syscall_return_slowpath arch/x86/entry/common.c:270 [inline] do_syscall_64+0x4a3/0x640 arch/x86/entry/common.c:297 entry_SYSCALL_64_after_hwframe+0x5e/0xd3 RIP: 0033:0x7f94e4676fab RSP: 002b:00007ffe61c70b30 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000004 RCX: 00007f94e4676fab RDX: 0000000000000000 RSI: 0000001b300215dc RDI: 0000000000000003 RBP: 00007f94e47e6980 R08: 0000000000000000 R09: 00000000d6a389d0 R10: 0000000000000000 R11: 0000000000000293 R12: 000000000014b04e R13: 00007ffe61c70c30 R14: 00007ffe61c70c50 R15: 0000000000000032 Code: c5 3e f7 ff eb d2 0f 1f 00 55 48 89 fd 48 83 ec 08 e8 43 7b cd ff 48 8d 7d 64 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 14 02 48 89 f8 83 e0 07 83 c0 03 38 d0 7c 04 84 d2 75 4f RIP: cdev_del+0x22/0x90 fs/char_dev.c:602 RSP: ffff88809e587ca0 ---[ end trace 5ceee1b19b73d1ee ]--- ---------------- Code disassembly (best guess), 1 bytes skipped: 0: 3e f7 ff ds idiv %edi 3: eb d2 jmp 0xffffffd7 5: 0f 1f 00 nopl (%rax) 8: 55 push %rbp 9: 48 89 fd mov %rdi,%rbp c: 48 83 ec 08 sub $0x8,%rsp 10: e8 43 7b cd ff callq 0xffcd7b58 15: 48 8d 7d 64 lea 0x64(%rbp),%rdi 19: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax 20: fc ff df 23: 48 89 fa mov %rdi,%rdx 26: 48 c1 ea 03 shr $0x3,%rdx * 2a: 0f b6 14 02 movzbl (%rdx,%rax,1),%edx <-- trapping instruction 2e: 48 89 f8 mov %rdi,%rax 31: 83 e0 07 and $0x7,%eax 34: 83 c0 03 add $0x3,%eax 37: 38 d0 cmp %dl,%al 39: 7c 04 jl 0x3f 3b: 84 d2 test %dl,%dl 3d: 75 4f jne 0x8e