netdev - [net 1/1] tipc: lock wakeup & inputq at tipc_link

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Message-ID: <1537906150-30955-1-git-send-email-jon.maloy@ericsson.com>
Date:   Tue, 25 Sep 2018 22:09:10 +0200
From:   Jon Maloy <jon.maloy@...csson.com>
To:     <davem@...emloft.net>, <netdev@...r.kernel.org>
CC:     <gordan.mihaljevic@...tech.com.au>, <tung.q.nguyen@...tech.com.au>,
        <hoang.h.le@...tech.com.au>, <jon.maloy@...csson.com>,
        <canh.d.luu@...tech.com.au>, <ying.xue@...driver.com>,
        <tipc-discussion@...ts.sourceforge.net>
Subject: [net  1/1] tipc: lock wakeup & inputq at tipc_link_reset()

From: Parthasarathy Bhuvaragan <parthasarathy.bhuvaragan@...csson.com>

In tipc_link_reset() we copy the wakeup queue to input queue using
skb_queue_splice_init(link->wakeupq, link->inputq).
This is performed without holding any locks. The lists might be
simultaneously be accessed by other cpu threads in tipc_sk_rcv(),
something leading to to random missing packets.

Signed-off-by: Parthasarathy Bhuvaragan <parthasarathy.bhuvaragan@...csson.com>
Signed-off-by: Jon Maloy <jon.maloy@...csson.com>
---
 net/tipc/link.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/net/tipc/link.c b/net/tipc/link.c
index b1f0bee..26cc033 100644
--- a/net/tipc/link.c
+++ b/net/tipc/link.c
@@ -841,9 +841,14 @@ void tipc_link_reset(struct tipc_link *l)
 	l->in_session = false;
 	l->session++;
 	l->mtu = l->advertised_mtu;
+	spin_lock_bh(&l->wakeupq.lock);
+	spin_lock_bh(&l->inputq->lock);
+	skb_queue_splice_init(&l->wakeupq, l->inputq);
+	spin_unlock_bh(&l->inputq->lock);
+	spin_unlock_bh(&l->wakeupq.lock);
+
 	__skb_queue_purge(&l->transmq);
 	__skb_queue_purge(&l->deferdq);
-	skb_queue_splice_init(&l->wakeupq, l->inputq);
 	__skb_queue_purge(&l->backlogq);
 	l->backlog[TIPC_LOW_IMPORTANCE].len = 0;
 	l->backlog[TIPC_MEDIUM_IMPORTANCE].len = 0;
-- 
2.1.4