* Re: [PATCH net-next] net: Separate the close_list and the unreg_list
2013-10-05 13:18 [PATCH net-next] net: Separate the close_list and the unreg_list Francesco Ruggeri
@ 2013-10-06 2:13 ` Eric W. Biederman
2013-10-06 2:26 ` [PATCH] net: Separate the close_list and the unreg_list v2 Eric W. Biederman
1 sibling, 0 replies; 5+ messages in thread
From: Eric W. Biederman @ 2013-10-06 2:13 UTC (permalink / raw)
To: Francesco Ruggeri; +Cc: netdev
Francesco Ruggeri <fruggeri@aristanetworks.com> writes:
> Hi Eric,
> I am running some more extensive tests with this patch and I ran into
> the crash below.
>
> It may be caused by
>
> @@ -1301,7 +1301,7 @@ int dev_close(struct net_device *dev)
> if (dev->flags & IFF_UP) {
> LIST_HEAD(single);
>
> - list_add(&dev->unreg_list, &single);
> + list_add(&dev->close_list, &single);
> dev_close_many(&single);
> list_del(&single);
> }
>
> dev_close_many expects net_devices to be linked by unreg_list.
> Let me know what you think.
Yes. There does appear to be a logic problem there.
Grr.
It looks like the least error prone approach is to simply have
dev_close_many consume it's list.
Can you verify this incremental change fixes it for you?
This changes all of the callers to build the close_list before
calling dev_close_many. Which makes it safe to muck with the close
list however we want.
---
diff --git a/net/core/dev.c b/net/core/dev.c
index c8db0bfc36d6..fa0b2b06c1a6 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1362,16 +1362,15 @@ static int __dev_close(struct net_device *dev)
static int dev_close_many(struct list_head *head)
{
struct net_device *dev, *tmp;
- LIST_HEAD(many);
- /* rollback_registered_many needs the original unmodified list */
- list_for_each_entry(dev, head, unreg_list)
- if (dev->flags & IFF_UP)
- list_add_tail(&dev->close_list, &many);
+ /* Remove the devices that don't need to be closed */
+ list_for_each_entry_safe(dev, tmp, head, close_list)
+ if (!(dev->flags & IFF_UP))
+ list_del_init(&dev->close_list);
- __dev_close_many(&many);
+ __dev_close_many(head);
- list_for_each_entry_safe(dev, tmp, &many, close_list) {
+ list_for_each_entry_safe(dev, tmp, head, close_list) {
rtmsg_ifinfo(RTM_NEWLINK, dev, IFF_UP|IFF_RUNNING);
call_netdevice_notifiers(NETDEV_DOWN, dev);
list_del_init(&dev->close_list);
@@ -5439,6 +5438,7 @@ static void net_set_todo(struct net_device *dev)
static void rollback_registered_many(struct list_head *head)
{
struct net_device *dev, *tmp;
+ LIST_HEAD(close_head);
BUG_ON(dev_boot_phase);
ASSERT_RTNL();
@@ -5461,7 +5461,9 @@ static void rollback_registered_many(struct list_head *head)
}
/* If device is running, close it first. */
- dev_close_many(head);
+ list_for_each_entry(dev, head, unreg_list)
+ list_add_tail(&dev->close_list, &close_head);
+ dev_close_many(&close_head);
list_for_each_entry(dev, head, unreg_list) {
/* And unlink it from device chain. */
^ permalink raw reply related [flat|nested] 5+ messages in thread* [PATCH] net: Separate the close_list and the unreg_list v2
2013-10-05 13:18 [PATCH net-next] net: Separate the close_list and the unreg_list Francesco Ruggeri
2013-10-06 2:13 ` Eric W. Biederman
@ 2013-10-06 2:26 ` Eric W. Biederman
2013-10-07 19:22 ` David Miller
1 sibling, 1 reply; 5+ messages in thread
From: Eric W. Biederman @ 2013-10-06 2:26 UTC (permalink / raw)
To: Francesco Ruggeri; +Cc: netdev
Separate the unreg_list and the close_list in dev_close_many preventing
dev_close_many from permuting the unreg_list. The permutations of the
unreg_list have resulted in cases where the loopback device is accessed
it has been freed in code such as dst_ifdown. Resulting in subtle memory
corruption.
This is the second bug from sharing the storage between the close_list
and the unreg_list. The issues that crop up with sharing are
apparently too subtle to show up in normal testing or usage, so let's
forget about being clever and use two separate lists.
v2: Make all callers pass in a close_list to dev_close_many
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
Sending the complete diff because this version is actually more
readable and more obviously correct.
include/linux/netdevice.h | 1 +
net/core/dev.c | 25 ++++++++++++++-----------
net/sched/sch_generic.c | 6 +++---
3 files changed, 18 insertions(+), 14 deletions(-)
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index f5cd464271bf..6d77e0f3cc10 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1143,6 +1143,7 @@ struct net_device {
struct list_head dev_list;
struct list_head napi_list;
struct list_head unreg_list;
+ struct list_head close_list;
/* directly linked devices, like slaves for bonding */
struct {
diff --git a/net/core/dev.c b/net/core/dev.c
index c25db20a4246..fa0b2b06c1a6 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1307,7 +1307,7 @@ static int __dev_close_many(struct list_head *head)
ASSERT_RTNL();
might_sleep();
- list_for_each_entry(dev, head, unreg_list) {
+ list_for_each_entry(dev, head, close_list) {
call_netdevice_notifiers(NETDEV_GOING_DOWN, dev);
clear_bit(__LINK_STATE_START, &dev->state);
@@ -1323,7 +1323,7 @@ static int __dev_close_many(struct list_head *head)
dev_deactivate_many(head);
- list_for_each_entry(dev, head, unreg_list) {
+ list_for_each_entry(dev, head, close_list) {
const struct net_device_ops *ops = dev->netdev_ops;
/*
@@ -1351,7 +1351,7 @@ static int __dev_close(struct net_device *dev)
/* Temporarily disable netpoll until the interface is down */
netpoll_rx_disable(dev);
- list_add(&dev->unreg_list, &single);
+ list_add(&dev->close_list, &single);
retval = __dev_close_many(&single);
list_del(&single);
@@ -1362,21 +1362,20 @@ static int __dev_close(struct net_device *dev)
static int dev_close_many(struct list_head *head)
{
struct net_device *dev, *tmp;
- LIST_HEAD(tmp_list);
- list_for_each_entry_safe(dev, tmp, head, unreg_list)
+ /* Remove the devices that don't need to be closed */
+ list_for_each_entry_safe(dev, tmp, head, close_list)
if (!(dev->flags & IFF_UP))
- list_move(&dev->unreg_list, &tmp_list);
+ list_del_init(&dev->close_list);
__dev_close_many(head);
- list_for_each_entry(dev, head, unreg_list) {
+ list_for_each_entry_safe(dev, tmp, head, close_list) {
rtmsg_ifinfo(RTM_NEWLINK, dev, IFF_UP|IFF_RUNNING);
call_netdevice_notifiers(NETDEV_DOWN, dev);
+ list_del_init(&dev->close_list);
}
- /* rollback_registered_many needs the complete original list */
- list_splice(&tmp_list, head);
return 0;
}
@@ -1397,7 +1396,7 @@ int dev_close(struct net_device *dev)
/* Block netpoll rx while the interface is going down */
netpoll_rx_disable(dev);
- list_add(&dev->unreg_list, &single);
+ list_add(&dev->close_list, &single);
dev_close_many(&single);
list_del(&single);
@@ -5439,6 +5438,7 @@ static void net_set_todo(struct net_device *dev)
static void rollback_registered_many(struct list_head *head)
{
struct net_device *dev, *tmp;
+ LIST_HEAD(close_head);
BUG_ON(dev_boot_phase);
ASSERT_RTNL();
@@ -5461,7 +5461,9 @@ static void rollback_registered_many(struct list_head *head)
}
/* If device is running, close it first. */
- dev_close_many(head);
+ list_for_each_entry(dev, head, unreg_list)
+ list_add_tail(&dev->close_list, &close_head);
+ dev_close_many(&close_head);
list_for_each_entry(dev, head, unreg_list) {
/* And unlink it from device chain. */
@@ -6257,6 +6259,7 @@ struct net_device *alloc_netdev_mqs(int sizeof_priv, const char *name,
INIT_LIST_HEAD(&dev->napi_list);
INIT_LIST_HEAD(&dev->unreg_list);
+ INIT_LIST_HEAD(&dev->close_list);
INIT_LIST_HEAD(&dev->link_watch_list);
INIT_LIST_HEAD(&dev->adj_list.upper);
INIT_LIST_HEAD(&dev->adj_list.lower);
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index e7121d29c4bd..7fc899a943a8 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -829,7 +829,7 @@ void dev_deactivate_many(struct list_head *head)
struct net_device *dev;
bool sync_needed = false;
- list_for_each_entry(dev, head, unreg_list) {
+ list_for_each_entry(dev, head, close_list) {
netdev_for_each_tx_queue(dev, dev_deactivate_queue,
&noop_qdisc);
if (dev_ingress_queue(dev))
@@ -848,7 +848,7 @@ void dev_deactivate_many(struct list_head *head)
synchronize_net();
/* Wait for outstanding qdisc_run calls. */
- list_for_each_entry(dev, head, unreg_list)
+ list_for_each_entry(dev, head, close_list)
while (some_qdisc_is_busy(dev))
yield();
}
@@ -857,7 +857,7 @@ void dev_deactivate(struct net_device *dev)
{
LIST_HEAD(single);
- list_add(&dev->unreg_list, &single);
+ list_add(&dev->close_list, &single);
dev_deactivate_many(&single);
list_del(&single);
}
--
1.7.5.4
^ permalink raw reply related [flat|nested] 5+ messages in thread