syzkaller has found reproducer for the following crash on  
ead68f216110170ec729e2c4dec0aad6d38259d7
git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.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


R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
WARNING: CPU: 1 PID: 3154 at drivers/tty/tty_ldisc.c:531 tty_ldisc_restore  
drivers/tty/tty_ldisc.c:531 [inline]
WARNING: CPU: 1 PID: 3154 at drivers/tty/tty_ldisc.c:531  
tty_set_ldisc+0x4c6/0x7a0 drivers/tty/tty_ldisc.c:599
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 3154 Comm: syz-executor0 Not tainted 4.15.0-rc4+ #144
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Call Trace:
  __dump_stack lib/dump_stack.c:17 [inline]
  dump_stack+0x194/0x257 lib/dump_stack.c:53
  panic+0x1e4/0x41c kernel/panic.c:183
  __warn+0x1dc/0x200 kernel/panic.c:547
  report_bug+0x211/0x2d0 lib/bug.c:184
  fixup_bug.part.11+0x37/0x80 arch/x86/kernel/traps.c:177
  fixup_bug arch/x86/kernel/traps.c:246 [inline]
  do_error_trap+0x2d7/0x3e0 arch/x86/kernel/traps.c:295
  do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:314
  invalid_op+0x22/0x40 arch/x86/entry/entry_64.S:1061
RIP: 0010:tty_ldisc_restore drivers/tty/tty_ldisc.c:531 [inline]
RIP: 0010:tty_set_ldisc+0x4c6/0x7a0 drivers/tty/tty_ldisc.c:599
RSP: 0018:ffff8801c85af970 EFLAGS: 00010293
RAX: ffff8801c849a4c0 RBX: ffff8801c851d480 RCX: ffffffff8287e3d6
RDX: 0000000000000000 RSI: 1ffff100390935b0 RDI: 0000000000000282
RBP: ffff8801c85af9c0 R08: 1ffff100390b5eee R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 00000000ffffffff
R13: ffff8801c851d9f0 R14: ffff8801ca162780 R15: fffffffffffffff4
  tiocsetd drivers/tty/tty_io.c:2319 [inline]
  tty_ioctl+0x492/0x1610 drivers/tty/tty_io.c:2563
  vfs_ioctl fs/ioctl.c:46 [inline]
  do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686
  C_SYSC_ioctl fs/compat_ioctl.c:1495 [inline]
  compat_SyS_ioctl+0x4ef/0x2a30 fs/compat_ioctl.c:1419
  do_syscall_32_irqs_on arch/x86/entry/common.c:327 [inline]
  do_fast_syscall_32+0x3ee/0xf9d arch/x86/entry/common.c:389
  entry_SYSENTER_compat+0x54/0x63 arch/x86/entry/entry_64_compat.S:125
RIP: 0023:0xf7fa6c79
RSP: 002b:000000000844f86c EFLAGS: 00000216 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000000005423
RDX: 0000000020fdd000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
Dumping ftrace buffer:
    (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..