releases/4.9.4/net-dsa-ensure-validity-of-dst-ds.patch

   1 From foo@baz Thu Jan 12 21:37:26 CET 2017
   2 From: Florian Fainelli <f.fainelli@gmail.com>
   3 Date: Mon, 9 Jan 2017 11:58:34 -0800
   4 Subject: net: dsa: Ensure validity of dst->ds[0]
   5
   6 From: Florian Fainelli <f.fainelli@gmail.com>
   7
   8
   9 [ Upstream commit faf3a932fbeb77860226a8323eacb835edc98648 ]
  10
  11 It is perfectly possible to have non zero indexed switches being present
  12 in a DSA switch tree, in such a case, we will be deferencing a NULL
  13 pointer while dsa_cpu_port_ethtool_{setup,restore}. Be more defensive
  14 and ensure that dst->ds[0] is valid before doing anything with it.
  15
  16 Fixes: 0c73c523cf73 ("net: dsa: Initialize CPU port ethtool ops per tree")
  17 Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
  18 Reviewed-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
  19 Signed-off-by: David S. Miller <davem@davemloft.net>
  20 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  21 ---
  22  net/dsa/dsa2.c |   11 +++++++----
  23  1 file changed, 7 insertions(+), 4 deletions(-)
  24
  25 --- a/net/dsa/dsa2.c
  26 +++ b/net/dsa/dsa2.c
  27 @@ -394,9 +394,11 @@ static int dsa_dst_apply(struct dsa_swit
  28                         return err;
  29         }
  30
  31 -       err = dsa_cpu_port_ethtool_setup(dst->ds[0]);
  32 -       if (err)
  33 -               return err;
  34 +       if (dst->ds[0]) {
  35 +               err = dsa_cpu_port_ethtool_setup(dst->ds[0]);
  36 +               if (err)
  37 +                       return err;
  38 +       }
  39
  40         /* If we use a tagging format that doesn't have an ethertype
  41          * field, make sure that all packets from this point on get
  42 @@ -433,7 +435,8 @@ static void dsa_dst_unapply(struct dsa_s
  43                 dsa_ds_unapply(dst, ds);
  44         }
  45
  46 -       dsa_cpu_port_ethtool_restore(dst->ds[0]);
  47 +       if (dst->ds[0])
  48 +               dsa_cpu_port_ethtool_restore(dst->ds[0]);
  49
  50         pr_info("DSA: tree %d unapplied\n", dst->tree);
  51         dst->applied = false;