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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: cb1b728096 ("tipc: eliminate race condition at multicast reception")
Signed-off-by: Lv Yunlong <lyl2019@mail.ustc.edu.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Lv Yunlong 2021-03-28 00:30:29 -07:00 committed by David S. Miller
parent 1bfb3dea96
commit 6bf24dc0cc
1 changed files with 1 additions and 1 deletions
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2
net/tipc/socket.c
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@ -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);