[PATCH] cfg80211: fix cfg80211_leave() locking

[PATCH] cfg80211: fix cfg80211_leave() locking

[Michal Kazior]

The beacon_interval was set unprotected by
wdev.mtx. This could possibly lead to inconsistent
cfg80211 states.

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
---
 net/wireless/ap.c   |  4 ++--
 net/wireless/core.c | 10 +++++-----
 net/wireless/core.h |  4 ++++
 net/wireless/mesh.c |  4 ++--
 4 files changed, 13 insertions(+), 9 deletions(-)

diff --git a/net/wireless/ap.c b/net/wireless/ap.c
index 3e02ade..bdad1f9 100644
--- a/net/wireless/ap.c
+++ b/net/wireless/ap.c
@@ -6,8 +6,8 @@
 #include "rdev-ops.h"
 
 
-static int __cfg80211_stop_ap(struct cfg80211_registered_device *rdev,
-			      struct net_device *dev, bool notify)
+int __cfg80211_stop_ap(struct cfg80211_registered_device *rdev,
+		       struct net_device *dev, bool notify)
 {
 	struct wireless_dev *wdev = dev->ieee80211_ptr;
 	int err;
diff --git a/net/wireless/core.c b/net/wireless/core.c
index 276cf93..55599f7 100644
--- a/net/wireless/core.c
+++ b/net/wireless/core.c
@@ -758,16 +758,16 @@ void cfg80211_leave(struct cfg80211_registered_device *rdev,
 
 	ASSERT_RTNL();
 
+	wdev_lock(wdev);
 	switch (wdev->iftype) {
 	case NL80211_IFTYPE_ADHOC:
-		cfg80211_leave_ibss(rdev, dev, true);
+		__cfg80211_leave_ibss(rdev, dev, true);
 		break;
 	case NL80211_IFTYPE_P2P_CLIENT:
 	case NL80211_IFTYPE_STATION:
 		if (rdev->sched_scan_req && dev == rdev->sched_scan_req->dev)
 			__cfg80211_stop_sched_scan(rdev, false);
 
-		wdev_lock(wdev);
 #ifdef CONFIG_CFG80211_WEXT
 		kfree(wdev->wext.ie);
 		wdev->wext.ie = NULL;
@@ -776,20 +776,20 @@ void cfg80211_leave(struct cfg80211_registered_device *rdev,
 #endif
 		cfg80211_disconnect(rdev, dev,
 				    WLAN_REASON_DEAUTH_LEAVING, true);
-		wdev_unlock(wdev);
 		break;
 	case NL80211_IFTYPE_MESH_POINT:
-		cfg80211_leave_mesh(rdev, dev);
+		__cfg80211_leave_mesh(rdev, dev);
 		break;
 	case NL80211_IFTYPE_AP:
 	case NL80211_IFTYPE_P2P_GO:
-		cfg80211_stop_ap(rdev, dev, true);
+		__cfg80211_stop_ap(rdev, dev, true);
 		break;
 	default:
 		break;
 	}
 
 	wdev->beacon_interval = 0;
+	wdev_unlock(wdev);
 }
 
 static int cfg80211_netdev_notifier_call(struct notifier_block *nb,
diff --git a/net/wireless/core.h b/net/wireless/core.h
index 3975ffa..912d822 100644
--- a/net/wireless/core.h
+++ b/net/wireless/core.h
@@ -275,6 +275,8 @@ int cfg80211_join_mesh(struct cfg80211_registered_device *rdev,
 		       struct net_device *dev,
 		       struct mesh_setup *setup,
 		       const struct mesh_config *conf);
+int __cfg80211_leave_mesh(struct cfg80211_registered_device *rdev,
+			  struct net_device *dev);
 int cfg80211_leave_mesh(struct cfg80211_registered_device *rdev,
 			struct net_device *dev);
 int cfg80211_set_mesh_channel(struct cfg80211_registered_device *rdev,
@@ -282,6 +284,8 @@ int cfg80211_set_mesh_channel(struct cfg80211_registered_device *rdev,
 			      struct cfg80211_chan_def *chandef);
 
 /* AP */
+int __cfg80211_stop_ap(struct cfg80211_registered_device *rdev,
+		       struct net_device *dev, bool notify);
 int cfg80211_stop_ap(struct cfg80211_registered_device *rdev,
 		     struct net_device *dev, bool notify);
 
diff --git a/net/wireless/mesh.c b/net/wireless/mesh.c
index 5af5cc6..b5c304e 100644
--- a/net/wireless/mesh.c
+++ b/net/wireless/mesh.c
@@ -262,8 +262,8 @@ int cfg80211_set_mesh_channel(struct cfg80211_registered_device *rdev,
 	return 0;
 }
 
-static int __cfg80211_leave_mesh(struct cfg80211_registered_device *rdev,
-				 struct net_device *dev)
+int __cfg80211_leave_mesh(struct cfg80211_registered_device *rdev,
+			  struct net_device *dev)
 {
 	struct wireless_dev *wdev = dev->ieee80211_ptr;
 	int err;
-- 
1.8.5.3

Re: [PATCH] cfg80211: fix cfg80211_leave() locking

[Johannes Berg]

On Fri, 2014-02-28 at 15:58 +0100, Michal Kazior wrote:
> The beacon_interval was set unprotected by
> wdev.mtx. This could possibly lead to inconsistent
> cfg80211 states.

Why not just this patch? The beacon_interval is already set to 0 in
stop_ap(), and is irrelevant for the other modes.

diff --git a/net/wireless/core.c b/net/wireless/core.c
index 010892b81a06..a3bf18d11609 100644
--- a/net/wireless/core.c
+++ b/net/wireless/core.c
@@ -788,8 +788,6 @@ void cfg80211_leave(struct cfg80211_registered_device *rdev,
 	default:
 		break;
 	}
-
-	wdev->beacon_interval = 0;
 }
 
 static int cfg80211_netdev_notifier_call(struct notifier_block *nb,


johannes

Re: [PATCH] cfg80211: fix cfg80211_leave() locking

[Michal Kazior]

On 3 March 2014 13:55, Johannes Berg <johannes@sipsolutions.net> wrote:
> On Fri, 2014-02-28 at 15:58 +0100, Michal Kazior wrote:
>> The beacon_interval was set unprotected by
>> wdev.mtx. This could possibly lead to inconsistent
>> cfg80211 states.
>
> Why not just this patch? The beacon_interval is already set to 0 in
> stop_ap(), and is irrelevant for the other modes.
>
> diff --git a/net/wireless/core.c b/net/wireless/core.c
> index 010892b81a06..a3bf18d11609 100644
> --- a/net/wireless/core.c
> +++ b/net/wireless/core.c
> @@ -788,8 +788,6 @@ void cfg80211_leave(struct cfg80211_registered_device *rdev,
>         default:
>                 break;
>         }
> -
> -       wdev->beacon_interval = 0;
>  }
>
>  static int cfg80211_netdev_notifier_call(struct notifier_block *nb,
>
>
> johannes

Good point. I was focused on locking changes (for my other patch) and
noticed the beacon_interval being unprotected and didn't look more
into it. Should I respin or are you going to apply your patch
yourself? Either way is fine with me.


Michał

Re: [PATCH] cfg80211: fix cfg80211_leave() locking

[Johannes Berg]

On Mon, 2014-03-03 at 14:07 +0100, Michal Kazior wrote:
> On 3 March 2014 13:55, Johannes Berg <johannes@sipsolutions.net> wrote:
> > On Fri, 2014-02-28 at 15:58 +0100, Michal Kazior wrote:
> >> The beacon_interval was set unprotected by
> >> wdev.mtx. This could possibly lead to inconsistent
> >> cfg80211 states.
> >
> > Why not just this patch? The beacon_interval is already set to 0 in
> > stop_ap(), and is irrelevant for the other modes.
> >
> > diff --git a/net/wireless/core.c b/net/wireless/core.c
> > index 010892b81a06..a3bf18d11609 100644
> > --- a/net/wireless/core.c
> > +++ b/net/wireless/core.c
> > @@ -788,8 +788,6 @@ void cfg80211_leave(struct cfg80211_registered_device *rdev,
> >         default:
> >                 break;
> >         }
> > -
> > -       wdev->beacon_interval = 0;
> >  }
> >
> >  static int cfg80211_netdev_notifier_call(struct notifier_block *nb,
> >
> >
> > johannes
> 
> Good point. I was focused on locking changes (for my other patch) and
> noticed the beacon_interval being unprotected and didn't look more
> into it. Should I respin or are you going to apply your patch
> yourself? Either way is fine with me.

I've got it.

johannes