RE: [PATCH 01/11] mwifiex: fixup error cases in mwifiex_add_virtual_intf()

[Xinming Hu]

Hi,

This patch serials looks fine, thanks.

> -----Original Message-----
> From: linux-wireless-owner@xxxxxxxxxxxxxxx
> [mailto:linux-wireless-owner@xxxxxxxxxxxxxxx] On Behalf Of Brian Norris
> Sent: 2017年5月13日 0:42
> To: Ganapathi Bhat; Nishant Sarmukadam
> Cc: linux-kernel@xxxxxxxxxxxxxxx; Dmitry Torokhov; Amitkumar Karwar; Kalle
> Valo; linux-wireless@xxxxxxxxxxxxxxx; Doug Anderson; Brian Norris
> Subject: [PATCH 01/11] mwifiex: fixup error cases in mwifiex_add_virtual_intf()
> 
> If we fail to add an interface in mwifiex_add_virtual_intf(), we might hit a
> BUG_ON() in the networking code, because we didn't tear things down
> properly. Among the problems:
> 
>  (a) when failing to allocate workqueues, we fail to unregister the
>      netdev before calling free_netdev()
>  (b) even if we do try to unregister the netdev, we're still holding the
>      rtnl lock, so the device never properly unregistered; we'll be at
>      state NETREG_UNREGISTERING, and then hit free_netdev()'s:
> 	BUG_ON(dev->reg_state != NETREG_UNREGISTERED);
>  (c) we're allocating some dependent resources (e.g., DFS workqueues)
>      after we've registered the interface; this may or may not cause
>      problems, but it's good practice to allocate these before registering
>  (d) we're not even trying to unwind anything when mwifiex_send_cmd() or
>      mwifiex_sta_init_cmd() fail
> 
> To fix these issues, let's:
> 
>  * add a stacked set of error handling labels, to keep error handling
>    consistent and properly ordered (resolving (a) and (d))
>  * move the workqueue allocations before the registration (to resolve
>    (c); also resolves (b) by avoiding error cases where we have to
>    unregister)
> 
> [Incidentally, it's pretty easy to interrupt the alloc_workqueue() in, e.g., the
> following:
> 
>   iw phy phy0 interface add mlan0 type station
> 
> by sending it SIGTERM.]
> 
> This bugfix covers commits like commit 7d652034d1a0 ("mwifiex: channel
> switch support for mwifiex"), but parts of this bug exist all the way back to the
> introduction of dynamic interface handling in commit
> 93a1df48d224 ("mwifiex: add cfg80211 handlers add/del_virtual_intf").
> 
> Cc: <stable@xxxxxxxxxxxxxxx>
> Signed-off-by: Brian Norris <briannorris@xxxxxxxxxxxx>
> ---
>  drivers/net/wireless/marvell/mwifiex/cfg80211.c | 71
> ++++++++++++-------------
>  1 file changed, 35 insertions(+), 36 deletions(-)
> 
> diff --git a/drivers/net/wireless/marvell/mwifiex/cfg80211.c
> b/drivers/net/wireless/marvell/mwifiex/cfg80211.c
> index 7ec06bf13413..025bc06a19d6 100644
> --- a/drivers/net/wireless/marvell/mwifiex/cfg80211.c
> +++ b/drivers/net/wireless/marvell/mwifiex/cfg80211.c
> @@ -2964,10 +2964,8 @@ struct wireless_dev
> *mwifiex_add_virtual_intf(struct wiphy *wiphy,
>  	if (!dev) {
>  		mwifiex_dbg(adapter, ERROR,
>  			    "no memory available for netdevice\n");
> -		memset(&priv->wdev, 0, sizeof(priv->wdev));
> -		priv->wdev.iftype = NL80211_IFTYPE_UNSPECIFIED;
> -		priv->bss_mode = NL80211_IFTYPE_UNSPECIFIED;
> -		return ERR_PTR(-ENOMEM);
> +		ret = -ENOMEM;
> +		goto err_alloc_netdev;
>  	}
> 
>  	mwifiex_init_priv_params(priv, dev);
> @@ -2976,11 +2974,11 @@ struct wireless_dev
> *mwifiex_add_virtual_intf(struct wiphy *wiphy,
>  	ret = mwifiex_send_cmd(priv, HostCmd_CMD_SET_BSS_MODE,
>  			       HostCmd_ACT_GEN_SET, 0, NULL, true);
>  	if (ret)
> -		return ERR_PTR(ret);
> +		goto err_set_bss_mode;
> 
>  	ret = mwifiex_sta_init_cmd(priv, false, false);
>  	if (ret)
> -		return ERR_PTR(ret);
> +		goto err_sta_init;
> 
>  	mwifiex_setup_ht_caps(&wiphy->bands[NL80211_BAND_2GHZ]->ht_cap,
> priv);
>  	if (adapter->is_hw_11ac_capable)
> @@ -3011,31 +3009,14 @@ struct wireless_dev
> *mwifiex_add_virtual_intf(struct wiphy *wiphy,
> 
>  	SET_NETDEV_DEV(dev, adapter->dev);
> 
> -	/* Register network device */
> -	if (register_netdevice(dev)) {
> -		mwifiex_dbg(adapter, ERROR,
> -			    "cannot register virtual network device\n");
> -		free_netdev(dev);
> -		priv->bss_mode = NL80211_IFTYPE_UNSPECIFIED;
> -		priv->netdev = NULL;
> -		memset(&priv->wdev, 0, sizeof(priv->wdev));
> -		priv->wdev.iftype = NL80211_IFTYPE_UNSPECIFIED;
> -		return ERR_PTR(-EFAULT);
> -	}
> -
>  	priv->dfs_cac_workqueue = alloc_workqueue("MWIFIEX_DFS_CAC%s",
>  						  WQ_HIGHPRI |
>  						  WQ_MEM_RECLAIM |
>  						  WQ_UNBOUND, 1, name);
>  	if (!priv->dfs_cac_workqueue) {
> -		mwifiex_dbg(adapter, ERROR,
> -			    "cannot register virtual network device\n");
> -		free_netdev(dev);
> -		priv->bss_mode = NL80211_IFTYPE_UNSPECIFIED;
> -		priv->netdev = NULL;
> -		memset(&priv->wdev, 0, sizeof(priv->wdev));
> -		priv->wdev.iftype = NL80211_IFTYPE_UNSPECIFIED;
> -		return ERR_PTR(-ENOMEM);
> +		mwifiex_dbg(adapter, ERROR, "cannot alloc DFS CAC queue\n");
> +		ret = -ENOMEM;
> +		goto err_alloc_cac;
>  	}
> 
>  	INIT_DELAYED_WORK(&priv->dfs_cac_work,
> mwifiex_dfs_cac_work_queue); @@ -3044,16 +3025,9 @@ struct wireless_dev
> *mwifiex_add_virtual_intf(struct wiphy *wiphy,
>  						      WQ_HIGHPRI | WQ_UNBOUND |
>  						      WQ_MEM_RECLAIM, 1, name);
>  	if (!priv->dfs_chan_sw_workqueue) {
> -		mwifiex_dbg(adapter, ERROR,
> -			    "cannot register virtual network device\n");
> -		free_netdev(dev);
> -		priv->bss_mode = NL80211_IFTYPE_UNSPECIFIED;
> -		priv->netdev = NULL;
> -		memset(&priv->wdev, 0, sizeof(priv->wdev));
> -		priv->wdev.iftype = NL80211_IFTYPE_UNSPECIFIED;
> -		destroy_workqueue(priv->dfs_cac_workqueue);
> -		priv->dfs_cac_workqueue = NULL;
> -		return ERR_PTR(-ENOMEM);
> +		mwifiex_dbg(adapter, ERROR, "cannot alloc DFS channel sw
> queue\n");
> +		ret = -ENOMEM;
> +		goto err_alloc_chsw;
>  	}
> 
>  	INIT_DELAYED_WORK(&priv->dfs_chan_sw_work,
> @@ -3061,6 +3035,13 @@ struct wireless_dev
> *mwifiex_add_virtual_intf(struct wiphy *wiphy,
> 
>  	sema_init(&priv->async_sem, 1);
> 
> +	/* Register network device */
> +	if (register_netdevice(dev)) {
> +		mwifiex_dbg(adapter, ERROR, "cannot register network device\n");
> +		ret = -EFAULT;
> +		goto err_reg_netdev;
> +	}
> +
>  	mwifiex_dbg(adapter, INFO,
>  		    "info: %s: Marvell 802.11 Adapter\n", dev->name);
> 
> @@ -3081,11 +3062,29 @@ struct wireless_dev
> *mwifiex_add_virtual_intf(struct wiphy *wiphy,
>  		adapter->curr_iface_comb.p2p_intf++;
>  		break;
>  	default:
> +		/* This should be dead code; checked above */
>  		mwifiex_dbg(adapter, ERROR, "type not supported\n");
>  		return ERR_PTR(-EINVAL);
>  	}
> 
>  	return &priv->wdev;
> +
> +err_reg_netdev:
> +	destroy_workqueue(priv->dfs_chan_sw_workqueue);
> +	priv->dfs_chan_sw_workqueue = NULL;
> +err_alloc_chsw:
> +	destroy_workqueue(priv->dfs_cac_workqueue);
> +	priv->dfs_cac_workqueue = NULL;
> +err_alloc_cac:
> +	free_netdev(dev);
> +	priv->netdev = NULL;
> +err_sta_init:
> +err_set_bss_mode:
> +err_alloc_netdev:
> +	memset(&priv->wdev, 0, sizeof(priv->wdev));
> +	priv->wdev.iftype = NL80211_IFTYPE_UNSPECIFIED;
> +	priv->bss_mode = NL80211_IFTYPE_UNSPECIFIED;
> +	return ERR_PTR(ret);
>  }
>  EXPORT_SYMBOL_GPL(mwifiex_add_virtual_intf);
> 

Regards,
Simon

> --
> 2.13.0.rc2.291.g57267f2277-goog