netdev - Re: [ovs-dev] [PATCH net] net: openvswitch: do not free vport if register

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Date:   Mon, 10 Jun 2019 13:49:38 -0700
From:   Gregory Rose <gvrose8192@...il.com>
To:     Taehee Yoo <ap420073@...il.com>, davem@...emloft.net,
        pshelar@....org, netdev@...r.kernel.org, dev@...nvswitch.org
Subject: Re: [ovs-dev] [PATCH net] net: openvswitch: do not free vport if
 register_netdevice() is failed.


On 6/9/2019 7:26 AM, Taehee Yoo wrote:
> In order to create an internal vport, internal_dev_create() is used and
> that calls register_netdevice() internally.
> If register_netdevice() fails, it calls dev->priv_destructor() to free
> private data of netdev. actually, a private data of this is a vport.
>
> Hence internal_dev_create() should not free and use a vport after failure
> of register_netdevice().
>
> Test command
>      ovs-dpctl add-dp bonding_masters
>
> Splat looks like:
> [ 1035.667767] kasan: GPF could be caused by NULL-ptr deref or user memory access
> [ 1035.675958] general protection fault: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN PTI
> [ 1035.676916] CPU: 1 PID: 1028 Comm: ovs-vswitchd Tainted: G    B             5.2.0-rc3+ #240
> [ 1035.676916] RIP: 0010:internal_dev_create+0x2e5/0x4e0 [openvswitch]
> [ 1035.676916] Code: 48 c1 ea 03 80 3c 02 00 0f 85 9f 01 00 00 4c 8b 23 48 b8 00 00 00 00 00 fc ff df 49 8d bc 24 60 05 00 00 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 86 01 00 00 49 8b bc 24 60 05 00 00 e8 e4 68 f4
> [ 1035.713720] RSP: 0018:ffff88810dcb7578 EFLAGS: 00010206
> [ 1035.713720] RAX: dffffc0000000000 RBX: ffff88810d13fe08 RCX: ffffffff84297704
> [ 1035.713720] RDX: 00000000000000ac RSI: 0000000000000000 RDI: 0000000000000560
> [ 1035.713720] RBP: 00000000ffffffef R08: fffffbfff0d3b881 R09: fffffbfff0d3b881
> [ 1035.713720] R10: 0000000000000001 R11: fffffbfff0d3b880 R12: 0000000000000000
> [ 1035.768776] R13: 0000607ee460b900 R14: ffff88810dcb7690 R15: ffff88810dcb7698
> [ 1035.777709] FS:  00007f02095fc980(0000) GS:ffff88811b400000(0000) knlGS:0000000000000000
> [ 1035.777709] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 1035.777709] CR2: 00007ffdf01d2f28 CR3: 0000000108258000 CR4: 00000000001006e0
> [ 1035.777709] Call Trace:
> [ 1035.777709]  ovs_vport_add+0x267/0x4f0 [openvswitch]
> [ 1035.777709]  new_vport+0x15/0x1e0 [openvswitch]
> [ 1035.777709]  ovs_vport_cmd_new+0x567/0xd10 [openvswitch]
> [ 1035.777709]  ? ovs_dp_cmd_dump+0x490/0x490 [openvswitch]
> [ 1035.777709]  ? __kmalloc+0x131/0x2e0
> [ 1035.777709]  ? genl_family_rcv_msg+0xa54/0x1030
> [ 1035.777709]  genl_family_rcv_msg+0x63a/0x1030
> [ 1035.777709]  ? genl_unregister_family+0x630/0x630
> [ 1035.841681]  ? debug_show_all_locks+0x2d0/0x2d0
> [ ... ]
>
> Fixes: cf124db566e6 ("net: Fix inconsistent teardown and release of private netdev state.")
> Signed-off-by: Taehee Yoo <ap420073@...il.com>
> ---
>   net/openvswitch/vport-internal_dev.c | 18 ++++++++++++------
>   1 file changed, 12 insertions(+), 6 deletions(-)
>
> diff --git a/net/openvswitch/vport-internal_dev.c b/net/openvswitch/vport-internal_dev.c
> index 26f71cbf7527..5993405c25c1 100644
> --- a/net/openvswitch/vport-internal_dev.c
> +++ b/net/openvswitch/vport-internal_dev.c
> @@ -170,7 +170,9 @@ static struct vport *internal_dev_create(const struct vport_parms *parms)
>   {
>   	struct vport *vport;
>   	struct internal_dev *internal_dev;
> +	struct net_device *dev;
>   	int err;
> +	bool free_vport = true;
>   
>   	vport = ovs_vport_alloc(0, &ovs_internal_vport_ops, parms);
>   	if (IS_ERR(vport)) {
> @@ -178,8 +180,9 @@ static struct vport *internal_dev_create(const struct vport_parms *parms)
>   		goto error;
>   	}
>   
> -	vport->dev = alloc_netdev(sizeof(struct internal_dev),
> -				  parms->name, NET_NAME_USER, do_setup);
> +	dev = alloc_netdev(sizeof(struct internal_dev),
> +			   parms->name, NET_NAME_USER, do_setup);
> +	vport->dev = dev;
>   	if (!vport->dev) {
>   		err = -ENOMEM;
>   		goto error_free_vport;
> @@ -200,8 +203,10 @@ static struct vport *internal_dev_create(const struct vport_parms *parms)
>   
>   	rtnl_lock();
>   	err = register_netdevice(vport->dev);
> -	if (err)
> +	if (err) {
> +		free_vport = false;
>   		goto error_unlock;
> +	}
>   
>   	dev_set_promiscuity(vport->dev, 1);
>   	rtnl_unlock();
> @@ -211,11 +216,12 @@ static struct vport *internal_dev_create(const struct vport_parms *parms)
>   
>   error_unlock:
>   	rtnl_unlock();
> -	free_percpu(vport->dev->tstats);
> +	free_percpu(dev->tstats);
>   error_free_netdev:
> -	free_netdev(vport->dev);
> +	free_netdev(dev);
>   error_free_vport:
> -	ovs_vport_free(vport);
> +	if (free_vport)
> +		ovs_vport_free(vport);
>   error:
>   	return ERR_PTR(err);
>   }

Reviewed-by: Greg Rose <gvrose8192@...il.com>