net/batman-advanced/patches/0004-batman-adv-Don-t-use-net_dev-after-dev_put.patch

   1 From 91235b4ca86709f2974fc954c2ff81fd8e5ac926 Mon Sep 17 00:00:00 2001
   2 From: Sven Eckelmann <sven.eckelmann@gmx.de>
   3 Date: Fri, 20 Aug 2010 19:16:11 +0000
   4 Subject: [PATCH 09/10] batman-adv: Don't use net_dev after dev_put
   5
   6 dev_put allows a device to be freed when all its references are dropped.
   7 After that we are not allowed to access that information anymore. Access
   8 to the data structure of a net_device must be surrounded a dev_hold
   9 and ended using dev_put.
  10
  11 batman-adv adds a device to its own management structure in
  12 hardif_add_interface and will release it in hardif_remove_interface.
  13 Thus it must hold a reference all the time between those functions to
  14 prevent any access to the already released net_device structure.
  15
  16 Reported-by: Tim Glaremin <Tim.Glaremin@web.de>
  17 Signed-off-by: Sven Eckelmann <sven.eckelmann@gmx.de>
  18 Cc: stable <stable@kernel.org>
  19 ---
  20  hard-interface.c |   11 ++++++-----
  21  1 files changed, 6 insertions(+), 5 deletions(-)
  22
  23 diff --git a/hard-interface.c b/hard-interface.c
  24 index 1670ec8..ce6819a 100644
  25 --- a/hard-interface.c
  26 +++ b/hard-interface.c
  27 @@ -196,8 +196,6 @@ static void hardif_activate_interface(struct net_device *net_dev,
  28         if (batman_if->if_status != IF_INACTIVE)
  29                 return;
  30
  31 -       dev_hold(batman_if->net_dev);
  32 -
  33         update_mac_addresses(batman_if);
  34         batman_if->if_status = IF_TO_BE_ACTIVATED;
  35
  36 @@ -224,8 +222,6 @@ static void hardif_deactivate_interface(struct net_device *net_dev,
  37            (batman_if->if_status != IF_TO_BE_ACTIVATED))
  38                 return;
  39
  40 -       dev_put(batman_if->net_dev);
  41 -
  42         batman_if->if_status = IF_INACTIVE;
  43
  44         bat_info(net_dev, "Interface deactivated: %s\n", batman_if->dev);
  45 @@ -322,12 +318,14 @@ static struct batman_if *hardif_add_interface(struct net_device *net_dev)
  46         if (ret != 1)
  47                 goto out;
  48
  49 +       dev_hold(net_dev);
  50 +
  51         batman_if = kmalloc(sizeof(struct batman_if), GFP_ATOMIC);
  52         if (!batman_if) {
  53                 printk(KERN_ERR "batman-adv:"
  54                        "Can't add interface (%s): out of memory\n",
  55                        net_dev->name);
  56 -               goto out;
  57 +               goto release_dev;
  58         }
  59
  60         batman_if->dev = kstrdup(net_dev->name, GFP_ATOMIC);
  61 @@ -348,6 +346,8 @@ free_dev:
  62         kfree(batman_if->dev);
  63  free_if:
  64         kfree(batman_if);
  65 +release_dev:
  66 +       dev_put(net_dev);
  67  out:
  68         return NULL;
  69  }
  70 @@ -376,6 +376,7 @@ static void hardif_remove_interface(struct batman_if *batman_if)
  71         batman_if->if_status = IF_TO_BE_REMOVED;
  72         list_del_rcu(&batman_if->list);
  73         sysfs_del_hardif(&batman_if->hardif_obj);
  74 +       dev_put(batman_if->net_dev);
  75         call_rcu(&batman_if->rcu, hardif_free_interface);
  76  }
  77
  78 --
  79 1.7.1
  80