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Subject[PATCH 4.12 029/196] mwifiex: fixup error cases in mwifiex_add_virtual_intf()
Date
4.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Brian Norris <briannorris@chromium.org>

commit 8535107aa4ef92520cbb9a4739563b389c5f8e2c upstream.

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").

Signed-off-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/net/wireless/marvell/mwifiex/cfg80211.c | 71 +++++++++++-------------
1 file changed, 35 insertions(+), 36 deletions(-)

--- 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
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
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

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
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

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
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);


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