Commit 355a901e6c ("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>
75a518b09f