• Kirill Smelkov's avatar
    sky2: Fix crash on receiving VLAN frames · 88dccf5b
    Kirill Smelkov authored
    After recent 86a9bad3 (net: vlan: add protocol argument to packet
    tagging functions) my sky2 started to crash on receive of tagged
    frames, with backtrace similar to
    
        #CRASH!!!
        vlan_do_receive
        __netif_receive_skb_core
        __netif_receive_skb
        netif_receive_skb
        sky2_poll
        ...
        __net_rx_action
        __do_softirq
    
    The problem turned out to be:
    
        1) sky2 copies small packets from ring on RX, and in its
           receive_copy() skb header is copied manually field, by field, and
           only for some fields;
    
        2) 86a9bad3  added skb->vlan_proto, which vlan_untag() or
           __vlan_hwaccel_put_tag() set, and which is later used in
           vlan_do_receive().
    
           That patch updated copy_skb_header() for newly introduced
           skb->vlan_proto, but overlooked the need to also copy it in sky2's
           receive_copy().
    
    Because of 2, we have the following scenario:
    
        - frame is received and tagged in a ring, by sky2_rx_tag(). Both
          skb->vlan_proto and skb->vlan_tci are set;
    
        - later skb is decided to be copied, but skb->vlan_proto is
          forgotten and becomes 0.
    
        - in the beginning of vlan_do_receive() we call
    
            __be16 vlan_proto = skb->vlan_proto;
            vlan_dev = vlan_find_dev(skb->dev, vlan_proto, vlan_id);
    
          which eventually invokes
    
            vlan_proto_idx(vlan_proto)
    
          and that routine BUGs for everything except ETH_P_8021Q and
          ETH_P_8021AD.
    
          Oops.
    
    Fix it.
    
    P.S.
    
    Stephen, I wonder, why copy_skb_header() is not used in
    sky2.c::receive_copy() ? Problems, where receive_copy was updated field
    by field showed several times already, e.g.
    
        3f42941b    (sky2: propogate rx hash when packet is copied)
        e072b3fa
    
        (sky2: fix receive length error in mixed non-VLAN/VLAN traffic)
    
    Cc: Patrick McHardy <kaber@trash.net>
    Cc: Stephen Hemminger <stephen@networkplumber.org>
    Cc: Mirko Lindner <mlindner@marvell.com>
    Signed-off-by: default avatarKirill Smelkov <kirr@mns.spb.ru>
    Acked-by: default avatarStephen Hemminger <stephen@networkplumber.org>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    88dccf5b
sky2.c 136 KB