linux-kernel - Re: [PATCH net] net: fix NULL pointer dereference in l3mdev_l3

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <94a34aa3-a823-4550-b16a-179e6f6d6292@huawei.com>
Date: Wed, 19 Mar 2025 10:07:03 +0800
From: Wang Liang <wangliang74@...wei.com>
To: David Ahern <dsahern@...nel.org>, Simon Horman <horms@...nel.org>
CC: <davem@...emloft.net>, <edumazet@...gle.com>, <kuba@...nel.org>,
	<pabeni@...hat.com>, <fw@...len.de>, <daniel@...earbox.net>,
	<yuehaibing@...wei.com>, <zhangchangzhong@...wei.com>,
	<netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net] net: fix NULL pointer dereference in l3mdev_l3_rcv


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?