Messages in this thread Patch in this message | | | Date | Tue, 24 Aug 2010 15:45:45 -0700 | From | Greg KH <> | Subject | [100/114] Staging: batman-adv: Dont use net_dev after dev_put |
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2.6.35-stable review patch. If anyone has any objections, please let us know.
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From: Sven Eckelmann <sven.eckelmann@gmx.de>
commit 51a00eaf6e008b60943af6ab68c17ac3622208dc upstream.
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@web.de> Signed-off-by: Sven Eckelmann <sven.eckelmann@gmx.de> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- drivers/staging/batman-adv/hard-interface.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-)
--- 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(st 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( (batman_if->if_status != IF_TO_BE_ACTIVATED)) return; - dev_put(batman_if->net_dev); - batman_if->if_status = IF_INACTIVE; printk(KERN_INFO "batman-adv:Interface deactivated: %s\n", @@ -321,12 +317,14 @@ static struct batman_if *hardif_add_inte if (ret != 1) goto out; + dev_hold(net_dev); + batman_if = kmalloc(sizeof(struct batman_if), GFP_ATOMIC); if (!batman_if) { printk(KERN_ERR "batman-adv:" "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); @@ -350,6 +348,8 @@ free_dev: kfree(batman_if->dev); free_if: kfree(batman_if); +release_dev: + dev_put(net_dev); out: return NULL; } @@ -378,6 +378,7 @@ static void hardif_remove_interface(stru 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); }
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