From: Lv Yunlong lyl2019@mail.ustc.edu.cn
[ Upstream commit 6bf24dc0cc0cc43b29ba344b66d78590e687e046 ]
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: cb1b728096f54 ("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 Signed-off-by: Sasha Levin sashal@kernel.org --- net/tipc/socket.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/tipc/socket.c b/net/tipc/socket.c index e795a8a2955b..5b18c6a46cfb 100644 --- a/net/tipc/socket.c +++ b/net/tipc/socket.c @@ -1244,7 +1244,7 @@ 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);