Date:   Fri, 03 Nov 2017 05:42:01 -0700
From:   syzbot 
        <bot+529dcc7acae97863327261a275c516477f0f4595@...kaller.appspotmail.com>
To:     ebiederm@...ssion.com, linux-kernel@...r.kernel.org,
        syzkaller-bugs@...glegroups.com
Subject: BUG: unable to handle kernel paging request in devpts_mntget

Hello,

syzkaller hit the following crash on  
36ef71cae353f88fd6e095e2aaa3e5953af1685d
git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/master
compiler: gcc (GCC) 7.1.1 20170620
.config is attached
Raw console output is attached.

syzkaller reproducer is attached. See https://goo.gl/kgGztJ
for information about syzkaller reproducers


IP: devpts_mntget+0x135/0x280 fs/devpts/inode.c:173
PGD 7fff4067 P4D 7fff4067 PUD 7fff3067 PMD 7fff2067 PTE 0
Oops: 0000 [#1] SMP KASAN
Dumping ftrace buffer:
    (ftrace buffer empty)
Modules linked in:
CPU: 0 PID: 4725 Comm: syz-executor2 Not tainted 4.14.0-rc5-next-20171018+  
#8
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
task: ffff88006ba222c0 task.stack: ffff880068f00000
RIP: 0010:devpts_mntget+0x135/0x280 fs/devpts/inode.c:173
RSP: 0018:ffff880068f07a50 EFLAGS: 00010a03
RAX: dffffc0000000000 RBX: ffffffffffffffed RCX: ffffffff81ce4ac0
RDX: 1ffffffffffffffe RSI: 0000000000000001 RDI: fffffffffffffff5
RBP: ffff880068f07ae0 R08: 0000000000000001 R09: 1ffff1000d1e0f05
R10: ffff880068f07760 R11: 0000000000000000 R12: 1ffff1000d1e0f4a
R13: ffff880068f07a70 R14: ffff88006bc44700 R15: ffff880068f07b20
FS:  00007f907b47d700(0000) GS:ffff88003ec00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffffbfffffffffe CR3: 000000003e167000 CR4: 00000000000006f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
  ptm_open_peer+0x11a/0x2f0 drivers/tty/pty.c:631
  tty_ioctl+0x50f/0x15f0 drivers/tty/tty_io.c:2621
  vfs_ioctl fs/ioctl.c:45 [inline]
  do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:685
  SYSC_ioctl fs/ioctl.c:700 [inline]
  SyS_ioctl+0x8f/0xc0 fs/ioctl.c:691
  entry_SYSCALL_64_fastpath+0x1f/0xbe
RIP: 0033:0x447c89
RSP: 002b:00007f907b47cbd8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f907b47d6cc RCX: 0000000000447c89
RDX: 00000000202c2000 RSI: 2000000000005441 RDI: 0000000000000000
RBP: 0000000000000082 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000008e08 R14: 00000000006ecea8 R15: 00007f907b47d700
Code: c1 ea 03 80 3c 02 00 0f 85 56 01 00 00 48 8b 5d 90 e8 e0 73 a0 ff 48  
8d 7b 08 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00  
0f 85 24 01 00 00 4c 8b 7b 08 48 b8 00 00 00 00 00
RIP: devpts_mntget+0x135/0x280 fs/devpts/inode.c:173 RSP: ffff880068f07a50
CR2: fffffbfffffffffe
---[ end trace 47949eeac6e2cd68 ]---
Kernel panic - not syncing: Fatal exception
Dumping ftrace buffer:
    (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..


---
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See https://goo.gl/tpsmEJ for details.
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View attachment "config.txt" of type "text/plain" (124357 bytes)

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