[4.2.y-ckt stable] Patch "mac80211: fix txq queue related crashes" has been added to the 4.2.y-ckt tree

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    mac80211: fix txq queue related crashes

to the linux-4.2.y-queue branch of the 4.2.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-4.2.y-queue

This patch is scheduled to be released in version 4.2.8-ckt7.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 4.2.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

---8<------------------------------------------------------------

>From 0fbce1f349421ecf205922911006f2e8dd99ee4c Mon Sep 17 00:00:00 2001
From: Michal Kazior <michal.kazior at tieto.com>
Date: Thu, 21 Jan 2016 14:23:07 +0100
Subject: mac80211: fix txq queue related crashes

commit 2a58d42c1e018ad514d4e23fd33fb2ded95d3ee6 upstream.

The driver can access the queue simultanously
while mac80211 tears down the interface. Without
spinlock protection this could lead to corrupting
sk_buff_head and subsequently to an invalid
pointer dereference.

Fixes: ba8c3d6f16a1 ("mac80211: add an intermediate software queue implementation")
Signed-off-by: Michal Kazior <michal.kazior at tieto.com>
Signed-off-by: Johannes Berg <johannes.berg at intel.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 net/mac80211/iface.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
index 436c423..2caf837 100644
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -975,7 +975,10 @@ static void ieee80211_do_stop(struct ieee80211_sub_if_data *sdata,
 	if (sdata->vif.txq) {
 		struct txq_info *txqi = to_txq_info(sdata->vif.txq);

+		spin_lock_bh(&txqi->queue.lock);
 		ieee80211_purge_tx_queue(&local->hw, &txqi->queue);
+		spin_unlock_bh(&txqi->queue.lock);
+
 		atomic_set(&sdata->txqs_len[txqi->txq.ac], 0);
 	}

--
2.7.4