From d7cc399e1227e74e44f78847d9732a228b46cc91 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Fri, 19 Apr 2019 16:02:03 -0700 Subject: [PATCH] tcp: properly reset skb->truesize for tx recycling tcp sendmsg() and sendpage() normally advance skb->data_len and skb->truesize by the payload added to an skb. But sendmsg(fd, ..., MSG_ZEROCOPY) has to account for whole pages, even if a single byte of payload is used in the page. This means that we can not assume skb->truesize can be adjusted by skb->data_len. We must instead overwrite its value. Otherwise skb->truesize is too big and can hit socket sndbuf limit, especially if the skb is recycled multiple times :/ Fixes: 472c2e07eef0 ("tcp: add one skb cache for tx") Signed-off-by: Eric Dumazet Cc: Soheil Hassas Yeganeh Cc: Willem de Bruijn Acked-by: Soheil Hassas Yeganeh Signed-off-by: David S. Miller --- net/ipv4/tcp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 603e770d59b3..f7567a3698eb 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -868,7 +868,7 @@ struct sk_buff *sk_stream_alloc_skb(struct sock *sk, int size, gfp_t gfp, if (likely(!size)) { skb = sk->sk_tx_skb_cache; if (skb && !skb_cloned(skb)) { - skb->truesize -= skb->data_len; + skb->truesize = SKB_TRUESIZE(skb_end_offset(skb)); sk->sk_tx_skb_cache = NULL; pskb_trim(skb, 0); INIT_LIST_HEAD(&skb->tcp_tsorted_anchor); -- 2.11.0