1. 02 Oct, 2012 2 commits
    • Ben Hutchings's avatar
      sfc: Fix maximum number of TSO segments and minimum TX queue size · 8a15a4b4
      Ben Hutchings authored
      [ Upstream commit 7e6d06f0 ]
      
      Currently an skb requiring TSO may not fit within a minimum-size TX
      queue.  The TX queue selected for the skb may stall and trigger the TX
      watchdog repeatedly (since the problem skb will be retried after the
      TX reset).  This issue is designated as CVE-2012-3412.
      
      Set the maximum number of TSO segments for our devices to 100.  This
      should make no difference to behaviour unless the actual MSS is less
      than about 700.  Increase the minimum TX queue size accordingly to
      allow for 2 worst-case skbs, so that there will definitely be space
      to add an skb after we wake a queue.
      
      To avoid invalidating existing configurations, change
      efx_ethtool_set_ringparam() to fix up values that are too small rather
      than returning -EINVAL.
      Signed-off-by: default avatarBen Hutchings <bhutchings@solarflare.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      8a15a4b4
    • Ben Hutchings's avatar
      net: Allow driver to limit number of GSO segments per skb · 7f8742ae
      Ben Hutchings authored
      [ Upstream commit 30b678d8 ]
      
      A peer (or local user) may cause TCP to use a nominal MSS of as little
      as 88 (actual MSS of 76 with timestamps).  Given that we have a
      sufficiently prodigious local sender and the peer ACKs quickly enough,
      it is nevertheless possible to grow the window for such a connection
      to the point that we will try to send just under 64K at once.  This
      results in a single skb that expands to 861 segments.
      
      In some drivers with TSO support, such an skb will require hundreds of
      DMA descriptors; a substantial fraction of a TX ring or even more than
      a full ring.  The TX queue selected for the skb may stall and trigger
      the TX watchdog repeatedly (since the problem skb will be retried
      after the TX reset).  This particularly affects sfc, for which the
      issue is designated as CVE-2012-3412.
      
      Therefore:
      1. Add the field net_device::gso_max_segs holding the device-specific
         limit.
      2. In netif_skb_features(), if the number of segments is too high then
         mask out GSO features to force fall back to software GSO.
      Signed-off-by: default avatarBen Hutchings <bhutchings@solarflare.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      7f8742ae
  2. 14 Sep, 2012 38 commits