• Ilya Dryomov's avatar
    libceph: validate con->state at the top of try_write() · 9c55ad1c
    Ilya Dryomov authored
    ceph_con_workfn() validates con->state before calling try_read() and
    then try_write().  However, try_read() temporarily releases con->mutex,
    notably in process_message() and ceph_con_in_msg_alloc(), opening the
    window for ceph_con_close() to sneak in, close the connection and
    release con->sock.  When try_write() is called on the assumption that
    con->state is still valid (i.e. not STANDBY or CLOSED), a NULL sock
    gets passed to the networking stack:
    
      BUG: unable to handle kernel NULL pointer dereference at 0000000000000020
      IP: selinux_socket_sendmsg+0x5/0x20
    
    Make sure con->state is valid at the top of try_write() and add an
    explicit BUG_ON for this, similar to try_read().
    
    Cc: stable@vger.kernel.org
    Link: https://tracker.ceph.com/issues/23706Signed-off-by: default avatarIlya Dryomov <idryomov@gmail.com>
    Reviewed-by: default avatarJason Dillaman <dillaman@redhat.com>
    9c55ad1c
messenger.c 88.2 KB