From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org, stable Cc: Greg Kroah-Hartman , Ben Hutchings , Eric Dumazet Subject: [PATCH 3.14 08/43] tcp: Fix crash in TCP Fast Open Date: Fri, 17 Apr 2015 15:28:42 +0200 Message-Id: <20150417132556.357164854@linuxfoundation.org> In-Reply-To: <20150417132556.014766917@linuxfoundation.org> References: <20150417132556.014766917@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ben Hutchings 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: Greg Kroah-Hartman --- net/ipv4/tcp_output.c | 1 + 1 file changed, 1 insertion(+) --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -2933,6 +2933,7 @@ static int tcp_send_syn_data(struct sock 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);