Commit 6bf24dc0 authored by Lv Yunlong's avatar Lv Yunlong Committed by David S. Miller
Browse files

net:tipc: Fix a double free in tipc_sk_mcast_rcv 



In the if(skb_peek(arrvq) == skb) branch, it calls __skb_dequeue(arrvq) to get
the skb by skb = skb_peek(arrvq). Then __skb_dequeue() unlinks the skb from arrvq
and returns the skb which equals to skb_peek(arrvq). After __skb_dequeue(arrvq)
finished, the skb is freed by kfree_skb(__skb_dequeue(arrvq)) in the first time.

Unfortunately, the same skb is freed in the second time by kfree_skb(skb) after
the branch completed.

My patch removes kfree_skb() in the if(skb_peek(arrvq) == skb) branch, because
this skb will be freed by kfree_skb(skb) finally.

Fixes: cb1b7280 ("tipc: eliminate race condition at multicast reception")
Signed-off-by: default avatarLv Yunlong <lyl2019@mail.ustc.edu.cn>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 1bfb3dea

net/tipc/socket.c

+1 −1
Original line number Diff line number Diff line
@@ -1265,7 +1265,7 @@ void tipc_sk_mcast_rcv(struct net *net, struct sk_buff_head *arrvq, 
		spin_lock_bh(&inputq->lock);

		if (skb_peek(arrvq) == skb) {

			skb_queue_splice_tail_init(&tmpq, inputq);

			kfree_skb(__skb_dequeue(arrvq));

			__skb_dequeue(arrvq);

		}

		spin_unlock_bh(&inputq->lock);

		__skb_queue_purge(&tmpq);