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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Amitkumar Karwar <akarwar@marvell.com>,
        Kalle Valo <kvalo@codeaurora.org>,
        Amit Pundir <amit.pundir@linaro.org>
Subject: [PATCH 4.4 70/86] mwifiex: Fix NULL pointer dereference in skb_dequeue()
Date:   Thu, 29 Nov 2018 15:12:35 +0100
Message-Id: <20181129140115.694668828@linuxfoundation.org>
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4.4-stable review patch.  If anyone has any objections, please let me know.

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

From: Amitkumar Karwar <akarwar@marvell.com>

commit c44c040300d7afd79294710313a4989683e2afb1 upstream.

At couple of places in cleanup path, we are just going through the
skb queue and freeing them without unlinking. This leads to a crash
when other thread tries to do skb_dequeue() and use already freed node.

The problem is freed by unlinking skb before freeing it.

Signed-off-by: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
[AmitP: Refactored to fix driver file path in linux-4.4.y]
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/net/wireless/mwifiex/cfg80211.c |    4 +++-
 drivers/net/wireless/mwifiex/wmm.c      |   12 +++++++++---
 2 files changed, 12 insertions(+), 4 deletions(-)

--- a/drivers/net/wireless/mwifiex/cfg80211.c
+++ b/drivers/net/wireless/mwifiex/cfg80211.c
@@ -2839,8 +2839,10 @@ int mwifiex_del_virtual_intf(struct wiph
 
 	mwifiex_stop_net_dev_queue(priv->netdev, adapter);
 
-	skb_queue_walk_safe(&priv->bypass_txq, skb, tmp)
+	skb_queue_walk_safe(&priv->bypass_txq, skb, tmp) {
+		skb_unlink(skb, &priv->bypass_txq);
 		mwifiex_write_data_complete(priv->adapter, skb, 0, -1);
+	}
 
 	if (netif_carrier_ok(priv->netdev))
 		netif_carrier_off(priv->netdev);
--- a/drivers/net/wireless/mwifiex/wmm.c
+++ b/drivers/net/wireless/mwifiex/wmm.c
@@ -501,8 +501,10 @@ mwifiex_wmm_del_pkts_in_ralist_node(stru
 	struct mwifiex_adapter *adapter = priv->adapter;
 	struct sk_buff *skb, *tmp;
 
-	skb_queue_walk_safe(&ra_list->skb_head, skb, tmp)
+	skb_queue_walk_safe(&ra_list->skb_head, skb, tmp) {
+		skb_unlink(skb, &ra_list->skb_head);
 		mwifiex_write_data_complete(adapter, skb, 0, -1);
+	}
 }
 
 /*
@@ -598,11 +600,15 @@ mwifiex_clean_txrx(struct mwifiex_privat
 		priv->adapter->if_ops.clean_pcie_ring(priv->adapter);
 	spin_unlock_irqrestore(&priv->wmm.ra_list_spinlock, flags);
 
-	skb_queue_walk_safe(&priv->tdls_txq, skb, tmp)
+	skb_queue_walk_safe(&priv->tdls_txq, skb, tmp) {
+		skb_unlink(skb, &priv->tdls_txq);
 		mwifiex_write_data_complete(priv->adapter, skb, 0, -1);
+	}
 
-	skb_queue_walk_safe(&priv->bypass_txq, skb, tmp)
+	skb_queue_walk_safe(&priv->bypass_txq, skb, tmp) {
+		skb_unlink(skb, &priv->bypass_txq);
 		mwifiex_write_data_complete(priv->adapter, skb, 0, -1);
+	}
 	atomic_set(&priv->adapter->bypass_tx_pending, 0);
 
 	idr_for_each(&priv->ack_status_frames, mwifiex_free_ack_frame, NULL);