From: Sven Eckelmann <[email protected]> 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 <[email protected]> Signed-off-by: Sven Eckelmann <[email protected]> Cc: stable <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- 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 _______________________________________________ devel mailing list [email protected] http://driverdev.linuxdriverproject.org/mailman/listinfo/devel
