* [PATCH net] net: fix NULL pointer dereference in l3mdev_l3_rcv
@ 2025-03-13 1:27 Wang Liang
2025-03-18 14:38 ` Simon Horman
0 siblings, 1 reply; 7+ messages in thread
From: Wang Liang @ 2025-03-13 1:27 UTC (permalink / raw)
To: dsahern, davem, edumazet, kuba, pabeni, horms, fw, daniel
Cc: yuehaibing, zhangchangzhong, wangliang74, netdev, linux-kernel
When delete l3s ipvlan:
ip link del link eth0 ipvlan1 type ipvlan mode l3s
This may cause a null pointer dereference:
Call trace:
ip_rcv_finish+0x48/0xd0
ip_rcv+0x5c/0x100
__netif_receive_skb_one_core+0x64/0xb0
__netif_receive_skb+0x20/0x80
process_backlog+0xb4/0x204
napi_poll+0xe8/0x294
net_rx_action+0xd8/0x22c
__do_softirq+0x12c/0x354
This is because l3mdev_l3_rcv() visit dev->l3mdev_ops after
ipvlan_l3s_unregister() assign the dev->l3mdev_ops to NULL. The process
like this:
(CPU1) | (CPU2)
l3mdev_l3_rcv() |
check dev->priv_flags: |
master = skb->dev; |
|
| ipvlan_l3s_unregister()
| set dev->priv_flags
| dev->l3mdev_ops = NULL;
|
visit master->l3mdev_ops |
Add lock for dev->priv_flags and dev->l3mdev_ops is too expensive. Resolve
this issue by add check for master->l3mdev_ops.
Fixes: c675e06a98a4 ("ipvlan: decouple l3s mode dependencies from other modes")
Signed-off-by: Wang Liang <wangliang74@huawei.com>
---
include/net/l3mdev.h | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/include/net/l3mdev.h b/include/net/l3mdev.h
index f7fe796e8429..b5af87a35a9f 100644
--- a/include/net/l3mdev.h
+++ b/include/net/l3mdev.h
@@ -165,6 +165,7 @@ static inline
struct sk_buff *l3mdev_l3_rcv(struct sk_buff *skb, u16 proto)
{
struct net_device *master = NULL;
+ const struct l3mdev_ops *l3mdev_ops;
if (netif_is_l3_slave(skb->dev))
master = netdev_master_upper_dev_get_rcu(skb->dev);
@@ -172,8 +173,12 @@ struct sk_buff *l3mdev_l3_rcv(struct sk_buff *skb, u16 proto)
netif_has_l3_rx_handler(skb->dev))
master = skb->dev;
- if (master && master->l3mdev_ops->l3mdev_l3_rcv)
- skb = master->l3mdev_ops->l3mdev_l3_rcv(master, skb, proto);
+ if (!master)
+ return skb;
+
+ l3mdev_ops = master->l3mdev_ops;
+ if (l3mdev_ops && l3mdev_ops->l3mdev_l3_rcv)
+ skb = l3mdev_ops->l3mdev_l3_rcv(master, skb, proto);
return skb;
}
--
2.34.1
^ permalink raw reply related [flat|nested] 7+ messages in thread* Re: [PATCH net] net: fix NULL pointer dereference in l3mdev_l3_rcv
2025-03-13 1:27 [PATCH net] net: fix NULL pointer dereference in l3mdev_l3_rcv Wang Liang
@ 2025-03-18 14:38 ` Simon Horman
2025-03-18 15:02 ` David Ahern
0 siblings, 1 reply; 7+ messages in thread
From: Simon Horman @ 2025-03-18 14:38 UTC (permalink / raw)
To: Wang Liang
Cc: dsahern, davem, edumazet, kuba, pabeni, fw, daniel, yuehaibing,
zhangchangzhong, netdev, linux-kernel
On Thu, Mar 13, 2025 at 09:27:13AM +0800, Wang Liang wrote:
> When delete l3s ipvlan:
>
> ip link del link eth0 ipvlan1 type ipvlan mode l3s
>
> This may cause a null pointer dereference:
>
> Call trace:
> ip_rcv_finish+0x48/0xd0
> ip_rcv+0x5c/0x100
> __netif_receive_skb_one_core+0x64/0xb0
> __netif_receive_skb+0x20/0x80
> process_backlog+0xb4/0x204
> napi_poll+0xe8/0x294
> net_rx_action+0xd8/0x22c
> __do_softirq+0x12c/0x354
>
> This is because l3mdev_l3_rcv() visit dev->l3mdev_ops after
> ipvlan_l3s_unregister() assign the dev->l3mdev_ops to NULL. The process
> like this:
>
> (CPU1) | (CPU2)
> l3mdev_l3_rcv() |
> check dev->priv_flags: |
> master = skb->dev; |
> |
> | ipvlan_l3s_unregister()
> | set dev->priv_flags
> | dev->l3mdev_ops = NULL;
> |
> visit master->l3mdev_ops |
>
> Add lock for dev->priv_flags and dev->l3mdev_ops is too expensive. Resolve
> this issue by add check for master->l3mdev_ops.
Hi Wang Liang,
It seems to me that checking master->l3mdev_ops like this is racy.
>
> Fixes: c675e06a98a4 ("ipvlan: decouple l3s mode dependencies from other modes")
> Signed-off-by: Wang Liang <wangliang74@huawei.com>
> ---
> include/net/l3mdev.h | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/include/net/l3mdev.h b/include/net/l3mdev.h
> index f7fe796e8429..b5af87a35a9f 100644
> --- a/include/net/l3mdev.h
> +++ b/include/net/l3mdev.h
> @@ -165,6 +165,7 @@ static inline
> struct sk_buff *l3mdev_l3_rcv(struct sk_buff *skb, u16 proto)
> {
> struct net_device *master = NULL;
> + const struct l3mdev_ops *l3mdev_ops;
If you end up respinning for some other reason, please rearrange the lines
above in reverse xmas tree order - longest line to shortest.
>
> if (netif_is_l3_slave(skb->dev))
> master = netdev_master_upper_dev_get_rcu(skb->dev);
> @@ -172,8 +173,12 @@ struct sk_buff *l3mdev_l3_rcv(struct sk_buff *skb, u16 proto)
> netif_has_l3_rx_handler(skb->dev))
> master = skb->dev;
>
> - if (master && master->l3mdev_ops->l3mdev_l3_rcv)
> - skb = master->l3mdev_ops->l3mdev_l3_rcv(master, skb, proto);
> + if (!master)
> + return skb;
> +
> + l3mdev_ops = master->l3mdev_ops;
> + if (l3mdev_ops && l3mdev_ops->l3mdev_l3_rcv)
> + skb = l3mdev_ops->l3mdev_l3_rcv(master, skb, proto);
>
> return skb;
> }
> --
> 2.34.1
>
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [PATCH net] net: fix NULL pointer dereference in l3mdev_l3_rcv
2025-03-18 14:38 ` Simon Horman
@ 2025-03-18 15:02 ` David Ahern
2025-03-19 2:07 ` Wang Liang
0 siblings, 1 reply; 7+ messages in thread
From: David Ahern @ 2025-03-18 15:02 UTC (permalink / raw)
To: Simon Horman, Wang Liang
Cc: davem, edumazet, kuba, pabeni, fw, daniel, yuehaibing,
zhangchangzhong, netdev, linux-kernel
On 3/18/25 3:38 PM, Simon Horman wrote:
> On Thu, Mar 13, 2025 at 09:27:13AM +0800, Wang Liang wrote:
>> When delete l3s ipvlan:
>>
>> ip link del link eth0 ipvlan1 type ipvlan mode l3s
>>
>> This may cause a null pointer dereference:
>>
>> Call trace:
>> ip_rcv_finish+0x48/0xd0
>> ip_rcv+0x5c/0x100
>> __netif_receive_skb_one_core+0x64/0xb0
>> __netif_receive_skb+0x20/0x80
>> process_backlog+0xb4/0x204
>> napi_poll+0xe8/0x294
>> net_rx_action+0xd8/0x22c
>> __do_softirq+0x12c/0x354
>>
>> This is because l3mdev_l3_rcv() visit dev->l3mdev_ops after
>> ipvlan_l3s_unregister() assign the dev->l3mdev_ops to NULL. The process
>> like this:
>>
>> (CPU1) | (CPU2)
>> l3mdev_l3_rcv() |
>> check dev->priv_flags: |
>> master = skb->dev; |
>> |
>> | ipvlan_l3s_unregister()
>> | set dev->priv_flags
>> | dev->l3mdev_ops = NULL;
>> |
>> visit master->l3mdev_ops |
>>
>> Add lock for dev->priv_flags and dev->l3mdev_ops is too expensive. Resolve
>> this issue by add check for master->l3mdev_ops.
>
> Hi Wang Liang,
>
> It seems to me that checking master->l3mdev_ops like this is racy.
vrf device leaves the l3mdev ops set; that is probably the better way to go.
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH net] net: fix NULL pointer dereference in l3mdev_l3_rcv
2025-03-18 15:02 ` David Ahern
@ 2025-03-19 2:07 ` Wang Liang
2025-03-19 2:08 ` David Ahern
2025-03-20 13:37 ` Simon Horman
0 siblings, 2 replies; 7+ messages in thread
From: Wang Liang @ 2025-03-19 2:07 UTC (permalink / raw)
To: David Ahern, Simon Horman
Cc: davem, edumazet, kuba, pabeni, fw, daniel, yuehaibing,
zhangchangzhong, netdev, linux-kernel
在 2025/3/18 23:02, David Ahern 写道:
> On 3/18/25 3:38 PM, Simon Horman wrote:
>> On Thu, Mar 13, 2025 at 09:27:13AM +0800, Wang Liang wrote:
>>> When delete l3s ipvlan:
>>>
>>> ip link del link eth0 ipvlan1 type ipvlan mode l3s
>>>
>>> This may cause a null pointer dereference:
>>>
>>> Call trace:
>>> ip_rcv_finish+0x48/0xd0
>>> ip_rcv+0x5c/0x100
>>> __netif_receive_skb_one_core+0x64/0xb0
>>> __netif_receive_skb+0x20/0x80
>>> process_backlog+0xb4/0x204
>>> napi_poll+0xe8/0x294
>>> net_rx_action+0xd8/0x22c
>>> __do_softirq+0x12c/0x354
>>>
>>> This is because l3mdev_l3_rcv() visit dev->l3mdev_ops after
>>> ipvlan_l3s_unregister() assign the dev->l3mdev_ops to NULL. The process
>>> like this:
>>>
>>> (CPU1) | (CPU2)
>>> l3mdev_l3_rcv() |
>>> check dev->priv_flags: |
>>> master = skb->dev; |
>>> |
>>> | ipvlan_l3s_unregister()
>>> | set dev->priv_flags
>>> | dev->l3mdev_ops = NULL;
>>> |
>>> visit master->l3mdev_ops |
>>>
>>> Add lock for dev->priv_flags and dev->l3mdev_ops is too expensive. Resolve
>>> this issue by add check for master->l3mdev_ops.
>> Hi Wang Liang,
>>
>> It seems to me that checking master->l3mdev_ops like this is racy.
> vrf device leaves the l3mdev ops set; that is probably the better way to go.
Thanks.
Only l3s ipvlan set the dev->l3mdev_ops to NULL at present, I will delete
'dev->l3mdev_ops = NULL' in ipvlan_l3s_unregister(), is that ok?
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH net] net: fix NULL pointer dereference in l3mdev_l3_rcv
2025-03-19 2:07 ` Wang Liang
@ 2025-03-19 2:08 ` David Ahern
2025-03-20 13:37 ` Simon Horman
1 sibling, 0 replies; 7+ messages in thread
From: David Ahern @ 2025-03-19 2:08 UTC (permalink / raw)
To: Wang Liang, Simon Horman
Cc: davem, edumazet, kuba, pabeni, fw, daniel, yuehaibing,
zhangchangzhong, netdev, linux-kernel
On 3/18/25 3:07 AM, Wang Liang wrote:
>>> It seems to me that checking master->l3mdev_ops like this is racy.
>> vrf device leaves the l3mdev ops set; that is probably the better way
>> to go.
>
> Thanks.
>
> Only l3s ipvlan set the dev->l3mdev_ops to NULL at present, I will delete
> 'dev->l3mdev_ops = NULL' in ipvlan_l3s_unregister(), is that ok?
>
I think that avoids the race you saw. vrf has had the ops for 9 years or
so and not seen that problem.
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH net] net: fix NULL pointer dereference in l3mdev_l3_rcv
2025-03-19 2:07 ` Wang Liang
2025-03-19 2:08 ` David Ahern
@ 2025-03-20 13:37 ` Simon Horman
2025-03-21 8:51 ` Wang Liang
1 sibling, 1 reply; 7+ messages in thread
From: Simon Horman @ 2025-03-20 13:37 UTC (permalink / raw)
To: Wang Liang
Cc: David Ahern, davem, edumazet, kuba, pabeni, fw, daniel,
yuehaibing, zhangchangzhong, netdev, linux-kernel
On Wed, Mar 19, 2025 at 10:07:03AM +0800, Wang Liang wrote:
>
> 在 2025/3/18 23:02, David Ahern 写道:
> > On 3/18/25 3:38 PM, Simon Horman wrote:
> > > On Thu, Mar 13, 2025 at 09:27:13AM +0800, Wang Liang wrote:
> > > > When delete l3s ipvlan:
> > > >
> > > > ip link del link eth0 ipvlan1 type ipvlan mode l3s
> > > >
> > > > This may cause a null pointer dereference:
> > > >
> > > > Call trace:
> > > > ip_rcv_finish+0x48/0xd0
> > > > ip_rcv+0x5c/0x100
> > > > __netif_receive_skb_one_core+0x64/0xb0
> > > > __netif_receive_skb+0x20/0x80
> > > > process_backlog+0xb4/0x204
> > > > napi_poll+0xe8/0x294
> > > > net_rx_action+0xd8/0x22c
> > > > __do_softirq+0x12c/0x354
> > > >
> > > > This is because l3mdev_l3_rcv() visit dev->l3mdev_ops after
> > > > ipvlan_l3s_unregister() assign the dev->l3mdev_ops to NULL. The process
> > > > like this:
> > > >
> > > > (CPU1) | (CPU2)
> > > > l3mdev_l3_rcv() |
> > > > check dev->priv_flags: |
> > > > master = skb->dev; |
> > > > |
> > > > | ipvlan_l3s_unregister()
> > > > | set dev->priv_flags
> > > > | dev->l3mdev_ops = NULL;
> > > > |
> > > > visit master->l3mdev_ops |
> > > >
> > > > Add lock for dev->priv_flags and dev->l3mdev_ops is too expensive. Resolve
> > > > this issue by add check for master->l3mdev_ops.
> > > Hi Wang Liang,
> > >
> > > It seems to me that checking master->l3mdev_ops like this is racy.
> > vrf device leaves the l3mdev ops set; that is probably the better way to go.
>
> Thanks.
>
> Only l3s ipvlan set the dev->l3mdev_ops to NULL at present, I will delete
> 'dev->l3mdev_ops = NULL' in ipvlan_l3s_unregister(), is that ok?
TBH, I am somewhat unclear on the correct tear down behaviour.
But I also understood that to be David's suggestion.
And I think that implementing that, and posting it as v2 would
be a good next step.
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH net] net: fix NULL pointer dereference in l3mdev_l3_rcv
2025-03-20 13:37 ` Simon Horman
@ 2025-03-21 8:51 ` Wang Liang
0 siblings, 0 replies; 7+ messages in thread
From: Wang Liang @ 2025-03-21 8:51 UTC (permalink / raw)
To: Simon Horman
Cc: David Ahern, davem, edumazet, kuba, pabeni, fw, daniel,
yuehaibing, zhangchangzhong, netdev, linux-kernel
在 2025/3/20 21:37, Simon Horman 写道:
> On Wed, Mar 19, 2025 at 10:07:03AM +0800, Wang Liang wrote:
>> 在 2025/3/18 23:02, David Ahern 写道:
>>> On 3/18/25 3:38 PM, Simon Horman wrote:
>>>> On Thu, Mar 13, 2025 at 09:27:13AM +0800, Wang Liang wrote:
>>>>> When delete l3s ipvlan:
>>>>>
>>>>> ip link del link eth0 ipvlan1 type ipvlan mode l3s
>>>>>
>>>>> This may cause a null pointer dereference:
>>>>>
>>>>> Call trace:
>>>>> ip_rcv_finish+0x48/0xd0
>>>>> ip_rcv+0x5c/0x100
>>>>> __netif_receive_skb_one_core+0x64/0xb0
>>>>> __netif_receive_skb+0x20/0x80
>>>>> process_backlog+0xb4/0x204
>>>>> napi_poll+0xe8/0x294
>>>>> net_rx_action+0xd8/0x22c
>>>>> __do_softirq+0x12c/0x354
>>>>>
>>>>> This is because l3mdev_l3_rcv() visit dev->l3mdev_ops after
>>>>> ipvlan_l3s_unregister() assign the dev->l3mdev_ops to NULL. The process
>>>>> like this:
>>>>>
>>>>> (CPU1) | (CPU2)
>>>>> l3mdev_l3_rcv() |
>>>>> check dev->priv_flags: |
>>>>> master = skb->dev; |
>>>>> |
>>>>> | ipvlan_l3s_unregister()
>>>>> | set dev->priv_flags
>>>>> | dev->l3mdev_ops = NULL;
>>>>> |
>>>>> visit master->l3mdev_ops |
>>>>>
>>>>> Add lock for dev->priv_flags and dev->l3mdev_ops is too expensive. Resolve
>>>>> this issue by add check for master->l3mdev_ops.
>>>> Hi Wang Liang,
>>>>
>>>> It seems to me that checking master->l3mdev_ops like this is racy.
>>> vrf device leaves the l3mdev ops set; that is probably the better way to go.
>> Thanks.
>>
>> Only l3s ipvlan set the dev->l3mdev_ops to NULL at present, I will delete
>> 'dev->l3mdev_ops = NULL' in ipvlan_l3s_unregister(), is that ok?
> TBH, I am somewhat unclear on the correct tear down behaviour.
> But I also understood that to be David's suggestion.
> And I think that implementing that, and posting it as v2 would
> be a good next step.
Ok. I will send a patch v2 later, please check it.
Thanks.
^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2025-03-21 8:51 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz follow: Atom feed
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2025-03-13 1:27 [PATCH net] net: fix NULL pointer dereference in l3mdev_l3_rcv Wang Liang
2025-03-18 14:38 ` Simon Horman
2025-03-18 15:02 ` David Ahern
2025-03-19 2:07 ` Wang Liang
2025-03-19 2:08 ` David Ahern
2025-03-20 13:37 ` Simon Horman
2025-03-21 8:51 ` Wang Liang
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