* [PATCH net-2.6] netns: assign NULL after pernet memory is freed @ 2010-04-26 11:18 Jiri Pirko 2010-04-26 12:07 ` Jiri Pirko 0 siblings, 1 reply; 5+ messages in thread From: Jiri Pirko @ 2010-04-26 11:18 UTC (permalink / raw) To: netdev; +Cc: davem, ebiederm This is needed to let know appropriate code (driver) know that pernet memory chunk was freed already. For example when driver has also registered netdev notifier, it can be called after memory is freed which could eventually lead to panic. Also a null check should be present in these notifiers. For example, previously, when drivers were responsible for pernet memory allocation/freeing, in pppoe this assign was done in pppoe_exit_net() right after pernet memory was freed. The check in notifier stayed (in pppoe_flush_dev called from pppoe_device_event) but makes no sense now without this patch. I already know about several notifiers where the check should be present, patches will follow up. Signed-off-by: Jiri Pirko <jpirko@redhat.com> diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c index bd8c471..29f622c 100644 --- a/net/core/net_namespace.c +++ b/net/core/net_namespace.c @@ -51,6 +51,7 @@ static void ops_free(const struct pernet_operations *ops, struct net *net) if (ops->id && ops->size) { int id = *ops->id; kfree(net_generic(net, id)); + net_assign_generic(net, id, NULL); } } ^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH net-2.6] netns: assign NULL after pernet memory is freed 2010-04-26 11:18 [PATCH net-2.6] netns: assign NULL after pernet memory is freed Jiri Pirko @ 2010-04-26 12:07 ` Jiri Pirko 2010-04-26 13:30 ` Jiri Pirko 2010-04-26 18:01 ` Eric W. Biederman 0 siblings, 2 replies; 5+ messages in thread From: Jiri Pirko @ 2010-04-26 12:07 UTC (permalink / raw) To: netdev; +Cc: davem, ebiederm Mon, Apr 26, 2010 at 01:18:07PM CEST, jpirko@redhat.com wrote: >This is needed to let know appropriate code (driver) know that pernet memory >chunk was freed already. For example when driver has also registered netdev >notifier, it can be called after memory is freed which could eventually lead >to panic. Also a null check should be present in these notifiers. > >For example, previously, when drivers were responsible for pernet memory >allocation/freeing, in pppoe this assign was done in pppoe_exit_net() right >after pernet memory was freed. The check in notifier stayed (in pppoe_flush_dev >called from pppoe_device_event) but makes no sense now without this patch. Hmm, thinking about this, since the life of pernet memories is directly connected with the life of net, as described by Eric, this should not be needed. So please scrach this one too. Sorry. Anyway, I'm still wondering how to prevent netdev_notifiers from using this when net is gone. Going to do more research, I'm probably missing something. > >I already know about several notifiers where the check should be present, >patches will follow up. > >Signed-off-by: Jiri Pirko <jpirko@redhat.com> > >diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c >index bd8c471..29f622c 100644 >--- a/net/core/net_namespace.c >+++ b/net/core/net_namespace.c >@@ -51,6 +51,7 @@ static void ops_free(const struct pernet_operations *ops, struct net *net) > if (ops->id && ops->size) { > int id = *ops->id; > kfree(net_generic(net, id)); >+ net_assign_generic(net, id, NULL); > } > } > ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH net-2.6] netns: assign NULL after pernet memory is freed 2010-04-26 12:07 ` Jiri Pirko @ 2010-04-26 13:30 ` Jiri Pirko 2010-04-26 18:05 ` Eric W. Biederman 2010-04-26 18:01 ` Eric W. Biederman 1 sibling, 1 reply; 5+ messages in thread From: Jiri Pirko @ 2010-04-26 13:30 UTC (permalink / raw) To: netdev; +Cc: davem, ebiederm Mon, Apr 26, 2010 at 02:07:17PM CEST, jpirko@redhat.com wrote: >Mon, Apr 26, 2010 at 01:18:07PM CEST, jpirko@redhat.com wrote: >>This is needed to let know appropriate code (driver) know that pernet memory >>chunk was freed already. For example when driver has also registered netdev >>notifier, it can be called after memory is freed which could eventually lead >>to panic. Also a null check should be present in these notifiers. >> >>For example, previously, when drivers were responsible for pernet memory >>allocation/freeing, in pppoe this assign was done in pppoe_exit_net() right >>after pernet memory was freed. The check in notifier stayed (in pppoe_flush_dev >>called from pppoe_device_event) but makes no sense now without this patch. > >Hmm, thinking about this, since the life of pernet memories is directly connected >with the life of net, as described by Eric, this should not be needed. So please >scrach this one too. Sorry. > >Anyway, I'm still wondering how to prevent netdev_notifiers from using this when >net is gone. Going to do more research, I'm probably missing something. Right, it becomes part of init_ns then. So this looks good then. One thing I can still imagine what may cause problem, since netdev_notifier is registered before register_pernet_device, the notifier can be called in between. So I think this should be reordered, am I right? Thanks Jirka > > >> >>I already know about several notifiers where the check should be present, >>patches will follow up. >> >>Signed-off-by: Jiri Pirko <jpirko@redhat.com> >> >>diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c >>index bd8c471..29f622c 100644 >>--- a/net/core/net_namespace.c >>+++ b/net/core/net_namespace.c >>@@ -51,6 +51,7 @@ static void ops_free(const struct pernet_operations *ops, struct net *net) >> if (ops->id && ops->size) { >> int id = *ops->id; >> kfree(net_generic(net, id)); >>+ net_assign_generic(net, id, NULL); >> } >> } >> ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH net-2.6] netns: assign NULL after pernet memory is freed 2010-04-26 13:30 ` Jiri Pirko @ 2010-04-26 18:05 ` Eric W. Biederman 0 siblings, 0 replies; 5+ messages in thread From: Eric W. Biederman @ 2010-04-26 18:05 UTC (permalink / raw) To: Jiri Pirko; +Cc: netdev, davem Jiri Pirko <jpirko@redhat.com> writes: > Mon, Apr 26, 2010 at 02:07:17PM CEST, jpirko@redhat.com wrote: >>Mon, Apr 26, 2010 at 01:18:07PM CEST, jpirko@redhat.com wrote: >>>This is needed to let know appropriate code (driver) know that pernet memory >>>chunk was freed already. For example when driver has also registered netdev >>>notifier, it can be called after memory is freed which could eventually lead >>>to panic. Also a null check should be present in these notifiers. >>> >>>For example, previously, when drivers were responsible for pernet memory >>>allocation/freeing, in pppoe this assign was done in pppoe_exit_net() right >>>after pernet memory was freed. The check in notifier stayed (in pppoe_flush_dev >>>called from pppoe_device_event) but makes no sense now without this patch. >> >>Hmm, thinking about this, since the life of pernet memories is directly connected >>with the life of net, as described by Eric, this should not be needed. So please >>scrach this one too. Sorry. >> >>Anyway, I'm still wondering how to prevent netdev_notifiers from using this when >>net is gone. Going to do more research, I'm probably missing something. > > Right, it becomes part of init_ns then. So this looks good then. One thing I can > still imagine what may cause problem, since netdev_notifier is registered before > register_pernet_device, the notifier can be called in between. So I think this > should be reordered, am I right? No. We guarantee that all network devices are either destroyed or moved to init_net with the appropriate notifications sent. Before we tear down the network namespace. This guarantees we won't have packets in flight when destroying the network subsystems. The moving and destroying of network devices should simply look like normal events, that don't need special handling. Eric ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH net-2.6] netns: assign NULL after pernet memory is freed 2010-04-26 12:07 ` Jiri Pirko 2010-04-26 13:30 ` Jiri Pirko @ 2010-04-26 18:01 ` Eric W. Biederman 1 sibling, 0 replies; 5+ messages in thread From: Eric W. Biederman @ 2010-04-26 18:01 UTC (permalink / raw) To: Jiri Pirko; +Cc: netdev, davem Jiri Pirko <jpirko@redhat.com> writes: > Mon, Apr 26, 2010 at 01:18:07PM CEST, jpirko@redhat.com wrote: >>This is needed to let know appropriate code (driver) know that pernet memory >>chunk was freed already. For example when driver has also registered netdev >>notifier, it can be called after memory is freed which could eventually lead >>to panic. Also a null check should be present in these notifiers. >> >>For example, previously, when drivers were responsible for pernet memory >>allocation/freeing, in pppoe this assign was done in pppoe_exit_net() right >>after pernet memory was freed. The check in notifier stayed (in pppoe_flush_dev >>called from pppoe_device_event) but makes no sense now without this patch. > > Hmm, thinking about this, since the life of pernet memories is directly connected > with the life of net, as described by Eric, this should not be needed. So please > scrach this one too. Sorry. > > Anyway, I'm still wondering how to prevent netdev_notifiers from using this when > net is gone. Going to do more research, I'm probably missing something. Also semenatically net_assign_generic is only guaranteed to work once, so assigning NULL is at least semantically wrong. Eric >>I already know about several notifiers where the check should be present, >>patches will follow up. >> >>Signed-off-by: Jiri Pirko <jpirko@redhat.com> >> >>diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c >>index bd8c471..29f622c 100644 >>--- a/net/core/net_namespace.c >>+++ b/net/core/net_namespace.c >>@@ -51,6 +51,7 @@ static void ops_free(const struct pernet_operations *ops, struct net *net) >> if (ops->id && ops->size) { >> int id = *ops->id; >> kfree(net_generic(net, id)); >>+ net_assign_generic(net, id, NULL); >> } >> } >> ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2010-04-26 18:05 UTC | newest] Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2010-04-26 11:18 [PATCH net-2.6] netns: assign NULL after pernet memory is freed Jiri Pirko 2010-04-26 12:07 ` Jiri Pirko 2010-04-26 13:30 ` Jiri Pirko 2010-04-26 18:05 ` Eric W. Biederman 2010-04-26 18:01 ` Eric W. Biederman
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