From: Sven Eckelmann <sven.eckelmann@xxxxxx>
dev_put allows a device to be freed when all its references are dropped.
After that we are not allowed to access that information anymore. Access
to the data structure of a net_device must be surrounded a dev_hold
and ended using dev_put.
batman-adv adds a device to its own management structure in
hardif_add_interface and will release it in hardif_remove_interface.
Thus it must hold a reference all the time between those functions to
prevent any access to the already released net_device structure.
Reported-by: Tim Glaremin <Tim.Glaremin@xxxxxx>
Signed-off-by: Sven Eckelmann <sven.eckelmann@xxxxxx>
Cc: stable <stable@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
---
drivers/staging/batman-adv/hard-interface.c | 11 ++++++-----
1 files changed, 6 insertions(+), 5 deletions(-)
diff --git a/drivers/staging/batman-adv/hard-interface.c b/drivers/staging/batman-adv/hard-interface.c
index 892166b..d08491e 100644
--- a/drivers/staging/batman-adv/hard-interface.c
+++ b/drivers/staging/batman-adv/hard-interface.c
@@ -194,8 +194,6 @@ static void hardif_activate_interface(struct net_device *net_dev,
if (batman_if->if_status != IF_INACTIVE)
return;
- dev_hold(batman_if->net_dev);
-
update_mac_addresses(batman_if);
batman_if->if_status = IF_TO_BE_ACTIVATED;
@@ -222,8 +220,6 @@ static void hardif_deactivate_interface(struct net_device *net_dev,
(batman_if->if_status != IF_TO_BE_ACTIVATED))
return;
- dev_put(batman_if->net_dev);
-
batman_if->if_status = IF_INACTIVE;
bat_info(net_dev, "Interface deactivated: %s\n", batman_if->dev);
@@ -318,11 +314,13 @@ static struct batman_if *hardif_add_interface(struct net_device *net_dev)
if (ret != 1)
goto out;
+ dev_hold(net_dev);
+
batman_if = kmalloc(sizeof(struct batman_if), GFP_ATOMIC);
if (!batman_if) {
pr_err("Can't add interface (%s): out of memory\n",
net_dev->name);
- goto out;
+ goto release_dev;
}
batman_if->dev = kstrdup(net_dev->name, GFP_ATOMIC);
@@ -346,6 +344,8 @@ free_dev:
kfree(batman_if->dev);
free_if:
kfree(batman_if);
+release_dev:
+ dev_put(net_dev);
out:
return NULL;
}
@@ -374,6 +374,7 @@ static void hardif_remove_interface(struct batman_if *batman_if)
batman_if->if_status = IF_TO_BE_REMOVED;
list_del_rcu(&batman_if->list);
sysfs_del_hardif(&batman_if->hardif_obj);
+ dev_put(batman_if->net_dev);
call_rcu(&batman_if->rcu, hardif_free_interface);
}
--
1.7.2
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