Why RHEL 6 machine crashes while trying to read from a tty in n_tty_read ?

Issue

• kernel BUG at drivers/char/n_tty.c:1713!
• Kernel panic due to NULL pointer dereference at n_tty_read
• Showing following traces

 #7 [ffff8806954d7ca0] do_page_fault at ffffffff814e0c3e
 #8 [ffff8806954d7cd0] page_fault at ffffffff814ddfe5
    [exception RIP: n_tty_read+713]
    RIP: ffffffff81305f19  RSP: ffff8806954d7d88  RFLAGS: 00010246
    RAX: 000000000000000d  RBX: ffff8806954d6000  RCX: 00007fafbda02034
    RDX: 0000000000000000  RSI: 00000000fffffff3  RDI: ffff88011229951c
    RBP: ffff8806954d7e98   R8: 0000000000000001   R9: 0000000000000001
    R10: 00000000ffffffff  R11: 0000000000000000  R12: ffff880112299000
    R13: 0000000000000000  R14: ffff880112299268  R15: ffff88011229951c
    ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
 #9 [ffff8806954d7ea0] tty_read at ffffffff81300b16
#10 [ffff8806954d7ef0] vfs_read at ffffffff81172f85
#11 [ffff8806954d7f30] sys_read at ffffffff811730c1