• holger@eitzenberger.org's avatar
    asix: fix BUG in receive path when lowering MTU · c5060cec
    holger@eitzenberger.org authored
    There is bug in the receive path of the asix driver at the time a
    packet is received larger than MTU size and DF bit set:
     BUG: unable to handle kernel paging request at 0000004000000001
     IP: [<ffffffff8126f65b>] skb_release_head_state+0x2d/0xd2
     Call Trace:
      [<ffffffff8126f86d>] ? skb_release_all+0x9/0x1e
      [<ffffffff8126f8ad>] ? __kfree_skb+0x9/0x6f
      [<ffffffffa00b4200>] ? asix_rx_fixup_internal+0xff/0x1ae [asix]
      [<ffffffffa00fb3dc>] ? usbnet_bh+0x4f/0x226 [usbnet]
    It is easily reproducable by setting an MTU of 512 e. g. and sending
    something like
      ping -s 1472 -c 1 -M do $SELF
    from another box.
    And this is because the rx->ax_skb is freed on error, but rx->ax_skb
    is not reset, and the size is not reset to zero in this case.
    And since the skb is added again to the usbnet->done skb queue it is
    accessing already freed memory, resulting in the BUG when freeing a
    2nd time.  I therefore think the value 0x0000004000000001 show in the
    trace is more or less random data.
    Signed-off-by: default avatarHolger Eitzenberger <holger@eitzenberger.org>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
asix_common.c 14.8 KB