Hello, syzbot found the following issue on: HEAD commit: 98477740 Merge branch 'rcu/urgent' of git://git.kernel.org.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=12641dab900000 kernel config: https://syzkaller.appspot.com/x/.config?x=5f4c828c9e3cef97 dashboard link: https://syzkaller.appspot.com/bug?extid=c49fe6089f295a05e6f8 compiler: gcc (GCC) 10.1.0-syz 20200507 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14eadc8d900000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1517d075900000 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+c49fe6089f295a05e6f8@xxxxxxxxxxxxxxxxxxxxxxxxx RBP: 00007ffee0265520 R08: 0000000000000002 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: ffffffffffffffff R13: 0000000000000005 R14: 0000000000000000 R15: 0000000000000000 general protection fault, probably for non-canonical address 0xdffffc000000000c: 0000 [#1] PREEMPT SMP KASAN KASAN: null-ptr-deref in range [0x0000000000000060-0x0000000000000067] CPU: 0 PID: 7451 Comm: syz-executor249 Not tainted 5.9.0-rc6-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:cdev_del+0x22/0x90 fs/char_dev.c:596 Code: b5 0f 1f 80 00 00 00 00 55 48 89 fd 48 83 ec 08 e8 d3 41 b3 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 48 RSP: 0018:ffffc90007f07b10 EFLAGS: 00010207 RAX: dffffc0000000000 RBX: ffff8880a16f3500 RCX: ffffffff841165ff RDX: 000000000000000c RSI: ffffffff81c2fc6d RDI: 0000000000000064 RBP: 0000000000000000 R08: 0000000000000001 R09: ffffffff8d0b7a67 R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880a16f3508 R13: ffff8880a17cd008 R14: ffff8880a6236420 R15: ffff8880a6236278 FS: 0000000000000000(0000) GS:ffff8880ae400000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f0288f8a710 CR3: 0000000094f1e000 CR4: 00000000001506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: tty_unregister_device drivers/tty/tty_io.c:3193 [inline] tty_unregister_device+0x112/0x1b0 drivers/tty/tty_io.c:3188 gsmld_detach_gsm drivers/tty/n_gsm.c:2411 [inline] gsmld_close+0xaa/0x260 drivers/tty/n_gsm.c:2480 tty_ldisc_close+0x110/0x190 drivers/tty/tty_ldisc.c:489 tty_ldisc_kill+0x94/0x150 drivers/tty/tty_ldisc.c:637 tty_ldisc_hangup+0x30b/0x680 drivers/tty/tty_ldisc.c:756 __tty_hangup.part.0+0x403/0x870 drivers/tty/tty_io.c:625 __tty_hangup drivers/tty/tty_io.c:575 [inline] tty_vhangup+0x1d/0x30 drivers/tty/tty_io.c:698 pty_close+0x3f5/0x550 drivers/tty/pty.c:79 tty_release+0x455/0xf60 drivers/tty/tty_io.c:1679 __fput+0x285/0x920 fs/file_table.c:281 task_work_run+0xdd/0x190 kernel/task_work.c:141 exit_task_work include/linux/task_work.h:25 [inline] do_exit+0xb7d/0x29f0 kernel/exit.c:806 do_group_exit+0x125/0x310 kernel/exit.c:903 __do_sys_exit_group kernel/exit.c:914 [inline] __se_sys_exit_group kernel/exit.c:912 [inline] __x64_sys_exit_group+0x3a/0x50 kernel/exit.c:912 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x440018 Code: Bad RIP value. RSP: 002b:00007ffee02654c8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000440018 RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 RBP: 00000000004bfd90 R08: 00000000000000e7 R09: ffffffffffffffd0 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 R13: 00000000006d2180 R14: 0000000000000000 R15: 0000000000000000 Modules linked in: ---[ end trace 98d732d1ef99b6c5 ]--- RIP: 0010:cdev_del+0x22/0x90 fs/char_dev.c:596 Code: b5 0f 1f 80 00 00 00 00 55 48 89 fd 48 83 ec 08 e8 d3 41 b3 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 48 RSP: 0018:ffffc90007f07b10 EFLAGS: 00010207 RAX: dffffc0000000000 RBX: ffff8880a16f3500 RCX: ffffffff841165ff RDX: 000000000000000c RSI: ffffffff81c2fc6d RDI: 0000000000000064 RBP: 0000000000000000 R08: 0000000000000001 R09: ffffffff8d0b7a67 R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880a16f3508 R13: ffff8880a17cd008 R14: ffff8880a6236420 R15: ffff8880a6236278 FS: 0000000000000000(0000) GS:ffff8880ae500000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ffd722a6000 CR3: 0000000094644000 CR4: 00000000001506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 --- This report is generated by a bot. 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