netdev - [PATCH net] sctp: increase sk_wmem_alloc when head->truesize is increased

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Date:   Mon, 26 Nov 2018 14:52:44 +0800
From:   Xin Long <lucien.xin@...il.com>
To:     network dev <netdev@...r.kernel.org>, linux-sctp@...r.kernel.org
Cc:     davem@...emloft.net,
        Marcelo Ricardo Leitner <marcelo.leitner@...il.com>,
        Neil Horman <nhorman@...driver.com>
Subject: [PATCH net] sctp: increase sk_wmem_alloc when head->truesize is increased

I changed to count sk_wmem_alloc by skb truesize instead of 1 to
fix the sk_wmem_alloc leak caused by later truesize's change in
xfrm in Commit 02968ccf0125 ("sctp: count sk_wmem_alloc by skb
truesize in sctp_packet_transmit").

But I should have also increased sk_wmem_alloc when head->truesize
is increased in sctp_packet_gso_append() as xfrm does. Otherwise,
sctp gso packet will cause sk_wmem_alloc underflow.

Fixes: 02968ccf0125 ("sctp: count sk_wmem_alloc by skb truesize in sctp_packet_transmit")
Signed-off-by: Xin Long <lucien.xin@...il.com>
---
 net/sctp/output.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/sctp/output.c b/net/sctp/output.c
index b0e74a3..025f48e 100644
--- a/net/sctp/output.c
+++ b/net/sctp/output.c
@@ -410,6 +410,7 @@ static void sctp_packet_gso_append(struct sk_buff *head, struct sk_buff *skb)
 	head->truesize += skb->truesize;
 	head->data_len += skb->len;
 	head->len += skb->len;
+	refcount_add(skb->truesize, &head->sk->sk_wmem_alloc);
 
 	__skb_header_release(skb);
 }
-- 
2.1.0