Patchwork [net-next] bonding: don't allow the master to become its slave

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Submitter Flavio Leitner
Date Aug. 9, 2012, 6:30 p.m.
Message ID <1344537049-11473-1-git-send-email-fbl@redhat.com>
Download mbox | patch
Permalink /patch/176213/
State Superseded
Delegated to: David Miller
Headers show

Comments

Flavio Leitner - Aug. 9, 2012, 6:30 p.m.
It doesn't make any sense to allow the master to become
its slave. That creates a loop of events causing a crash.

Reported-by: Leonardo Chiquitto <lchiquitto@suse.com>
Signed-off-by: Flavio Leitner <fbl@redhat.com>
---
 drivers/net/bonding/bond_main.c | 5 +++++
 1 file changed, 5 insertions(+)
Leonardo Chiquitto - Aug. 9, 2012, 6:45 p.m.
>>> On 8/9/2012 at 03:30 PM, Flavio Leitner <fbl@redhat.com> wrote: 
> It doesn't make any sense to allow the master to become
> its slave. That creates a loop of events causing a crash.
> 
> Reported-by: Leonardo Chiquitto <lchiquitto@suse.com>
> Signed-off-by: Flavio Leitner <fbl@redhat.com>
> ---
>  drivers/net/bonding/bond_main.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
> index 6fae5f3..5407b44 100644
> --- a/drivers/net/bonding/bond_main.c
> +++ b/drivers/net/bonding/bond_main.c
> @@ -1505,6 +1505,11 @@ int bond_enslave(struct net_device *bond_dev, struct 
> net_device *slave_dev)
>  	int link_reporting;
>  	int res = 0;
>  
> +	if (bond_dev == slave_dev) {
> +		pr_err("%s: Error: cannot enslave itself.\n", bond_dev->name);
> +		return -EINVAL;
> +	}
> +
>  	if (!bond->params.use_carrier && slave_dev->ethtool_ops == NULL &&
>  		slave_ops->ndo_do_ioctl == NULL) {
>  		pr_warning("%s: Warning: no link monitoring support for %s\n",

I've tested it here and confirm it prevents the crash.

Tested-by: Leonardo Chiquitto <lchiquitto@suse.com>

Thanks,
Leonardo

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Ben Hutchings - Aug. 9, 2012, 7:03 p.m.
On Thu, 2012-08-09 at 15:30 -0300, Flavio Leitner wrote:
> It doesn't make any sense to allow the master to become
> its slave. That creates a loop of events causing a crash.

What if there are other intermediate devices, e.g. the slave is a VLAN
sub-device of the bond?  And doesn't team also have this problem?

I think a more general check for such loops might be required.

Ben.

> Reported-by: Leonardo Chiquitto <lchiquitto@suse.com>
> Signed-off-by: Flavio Leitner <fbl@redhat.com>
> ---
>  drivers/net/bonding/bond_main.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
> index 6fae5f3..5407b44 100644
> --- a/drivers/net/bonding/bond_main.c
> +++ b/drivers/net/bonding/bond_main.c
> @@ -1505,6 +1505,11 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev)
>  	int link_reporting;
>  	int res = 0;
>  
> +	if (bond_dev == slave_dev) {
> +		pr_err("%s: Error: cannot enslave itself.\n", bond_dev->name);
> +		return -EINVAL;
> +	}
> +
>  	if (!bond->params.use_carrier && slave_dev->ethtool_ops == NULL &&
>  		slave_ops->ndo_do_ioctl == NULL) {
>  		pr_warning("%s: Warning: no link monitoring support for %s\n",
Flavio Leitner - Aug. 9, 2012, 7:39 p.m.
On Thu, 9 Aug 2012 20:03:23 +0100
Ben Hutchings <bhutchings@solarflare.com> wrote:

> On Thu, 2012-08-09 at 15:30 -0300, Flavio Leitner wrote:
> > It doesn't make any sense to allow the master to become
> > its slave. That creates a loop of events causing a crash.
> 
> What if there are other intermediate devices, e.g. the slave is a VLAN
> sub-device of the bond?  And doesn't team also have this problem?
> 
> I think a more general check for such loops might be required.

Maybe patching netdev_set_master() to fail in the loop case is
the way to go.  That would work for bonding, team and bridge.

What you think?

fbl
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Jiri Pirko - Aug. 9, 2012, 7:54 p.m.
Thu, Aug 09, 2012 at 09:03:23PM CEST, bhutchings@solarflare.com wrote:
>On Thu, 2012-08-09 at 15:30 -0300, Flavio Leitner wrote:
>> It doesn't make any sense to allow the master to become
>> its slave. That creates a loop of events causing a crash.
>
>What if there are other intermediate devices, e.g. the slave is a VLAN
>sub-device of the bond?  And doesn't team also have this problem?

Yes, it does.

>
>I think a more general check for such loops might be required.

I agree.
>
>Ben.
>
>> Reported-by: Leonardo Chiquitto <lchiquitto@suse.com>
>> Signed-off-by: Flavio Leitner <fbl@redhat.com>
>> ---
>>  drivers/net/bonding/bond_main.c | 5 +++++
>>  1 file changed, 5 insertions(+)
>> 
>> diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
>> index 6fae5f3..5407b44 100644
>> --- a/drivers/net/bonding/bond_main.c
>> +++ b/drivers/net/bonding/bond_main.c
>> @@ -1505,6 +1505,11 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev)
>>  	int link_reporting;
>>  	int res = 0;
>>  
>> +	if (bond_dev == slave_dev) {
>> +		pr_err("%s: Error: cannot enslave itself.\n", bond_dev->name);
>> +		return -EINVAL;
>> +	}
>> +
>>  	if (!bond->params.use_carrier && slave_dev->ethtool_ops == NULL &&
>>  		slave_ops->ndo_do_ioctl == NULL) {
>>  		pr_warning("%s: Warning: no link monitoring support for %s\n",
>
>-- 
>Ben Hutchings, Staff Engineer, Solarflare
>Not speaking for my employer; that's the marketing department's job.
>They asked us to note that Solarflare product names are trademarked.
>
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Jiri Pirko - Aug. 9, 2012, 7:55 p.m.
Thu, Aug 09, 2012 at 09:39:06PM CEST, fbl@redhat.com wrote:
>On Thu, 9 Aug 2012 20:03:23 +0100
>Ben Hutchings <bhutchings@solarflare.com> wrote:
>
>> On Thu, 2012-08-09 at 15:30 -0300, Flavio Leitner wrote:
>> > It doesn't make any sense to allow the master to become
>> > its slave. That creates a loop of events causing a crash.
>> 
>> What if there are other intermediate devices, e.g. the slave is a VLAN
>> sub-device of the bond?  And doesn't team also have this problem?
>> 
>> I think a more general check for such loops might be required.
>
>Maybe patching netdev_set_master() to fail in the loop case is
>the way to go.  That would work for bonding, team and bridge.
>
>What you think?


How about other devices who do not use "->master" like vlan, macvlan?
>
>fbl
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Patch

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 6fae5f3..5407b44 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -1505,6 +1505,11 @@  int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev)
 	int link_reporting;
 	int res = 0;
 
+	if (bond_dev == slave_dev) {
+		pr_err("%s: Error: cannot enslave itself.\n", bond_dev->name);
+		return -EINVAL;
+	}
+
 	if (!bond->params.use_carrier && slave_dev->ethtool_ops == NULL &&
 		slave_ops->ndo_do_ioctl == NULL) {
 		pr_warning("%s: Warning: no link monitoring support for %s\n",