Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965718AbbD0Vvj (ORCPT ); Mon, 27 Apr 2015 17:51:39 -0400 Received: from ip4-83-240-67-251.cust.nbox.cz ([83.240.67.251]:49594 "EHLO ip4-83-240-18-248.cust.nbox.cz" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753168AbbD0Vc5 (ORCPT ); Mon, 27 Apr 2015 17:32:57 -0400 From: Jiri Slaby To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Ben Hutchings , Jiri Slaby Subject: [PATCH 3.12 19/83] tcp: Fix crash in TCP Fast Open Date: Mon, 27 Apr 2015 23:31:50 +0200 Message-Id: <221ff9c56696e9e02d39ecb844528ebb4f8abf0f.1430159990.git.jslaby@suse.cz> X-Mailer: git-send-email 2.3.5 In-Reply-To: <3426bb8de3a655aa6668e92ee92eb35f0db86582.1430159990.git.jslaby@suse.cz> References: <3426bb8de3a655aa6668e92ee92eb35f0db86582.1430159990.git.jslaby@suse.cz> In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1824 Lines: 49 From: Ben Hutchings 3.12-stable review patch. If anyone has any objections, please let me know. =============== Commit 355a901e6cf1 ("tcp: make connect() mem charging friendly") changed tcp_send_syn_data() to perform an open-coded copy of the 'syn' skb rather than using skb_copy_expand(). The open-coded copy does not cover the skb_shared_info::gso_segs field, so in the new skb it is left set to 0. When this commit was backported into stable branches between 3.10.y and 3.16.7-ckty inclusive, it triggered the BUG() in tcp_transmit_skb(). Since Linux 3.18 the GSO segment count is kept in the tcp_skb_cb::tcp_gso_segs field and tcp_send_syn_data() does copy the tcp_skb_cb structure to the new skb, so mainline and newer stable branches are not affected. Set skb_shared_info::gso_segs to the correct value of 1. Signed-off-by: Ben Hutchings Acked-by: Eric Dumazet Signed-off-by: Jiri Slaby --- net/ipv4/tcp_output.c | 1 + 1 file changed, 1 insertion(+) diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index e07ccba040be..56db79dbc633 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -2919,6 +2919,7 @@ static int tcp_send_syn_data(struct sock *sk, struct sk_buff *syn) goto fallback; syn_data->ip_summed = CHECKSUM_PARTIAL; memcpy(syn_data->cb, syn->cb, sizeof(syn->cb)); + skb_shinfo(syn_data)->gso_segs = 1; if (unlikely(memcpy_fromiovecend(skb_put(syn_data, space), fo->data->msg_iov, 0, space))) { kfree_skb(syn_data); -- 2.3.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/