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authorBen Hutchings <ben@decadent.org.uk>2015-04-15 19:00:32 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-04-19 10:11:06 +0200
commit79ea2bfc7d9cac1949bec2cb09b622becb7d54b6 (patch)
tree184bd8835ecbf65f1e7dea82895b3820316d5a3f /net
parent93aad6489861adb737296b48c9f4484ab7b04b7c (diff)
downloadlinux-linaro-stable-79ea2bfc7d9cac1949bec2cb09b622becb7d54b6.tar.gz
tcp: Fix crash in TCP Fast Open
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 <ben@decadent.org.uk> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net')
-rw-r--r--net/ipv4/tcp_output.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index d0c310801479..96f64e59d70c 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -2933,6 +2933,7 @@ 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);