From patchwork Wed Nov 7 23:42:34 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: tcp: Avoid infinite loop on recvmsg bug Date: Wed, 07 Nov 2012 13:42:34 -0000 From: Eric Dumazet X-Patchwork-Id: 197739 Message-Id: <1352331754.2748.14.camel@edumazet-glaptop> To: Julius Werner Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org, Patrick McHardy , Hideaki YOSHIFUJI , James Morris , Alexey Kuznetsov , "David S. Miller" , Dave Jones , Sameer Nanda , Mandeep Singh Baines On Wed, 2012-11-07 at 15:33 -0800, Eric Dumazet wrote: > So you probably are fighting a bug we already fixed in upstream kernel. > > (commit c8628155ece363 "tcp: reduce out_of_order memory use" did not > played well with cloned skbs.) > > This issue was already discussed on netdev in the past. If you use a 3.4 kernel, you want the following patch. (I guess you could reproduce the crash easily running a tcpdump in //) --- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 257b617..9f8f68c 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -4496,7 +4496,9 @@ static void tcp_data_queue_ofo(struct sock *sk, struct sk_buff *skb) * to avoid future tcp_collapse_ofo_queue(), * probably the most expensive function in tcp stack. */ - if (skb->len <= skb_tailroom(skb1) && !tcp_hdr(skb)->fin) { + if (skb->len <= skb_tailroom(skb1) && + !tcp_hdr(skb)->fin && + !skb_cloned(skb1)) { NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPRCVCOALESCE); BUG_ON(skb_copy_bits(skb, 0,