4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Eric Dumazet edumazet@google.com
[ Upstream commit a6ca7abe53633d08eea1c6756cb49c9b2d4c90bf ]
This patch fixes the following lockdep splat in inet_csk_route_req()
lockdep_rcu_suspicious inet_csk_route_req tcp_v4_send_synack tcp_rtx_synack inet_rtx_syn_ack tcp_fastopen_synack_time tcp_retransmit_timer tcp_write_timer_handler tcp_write_timer call_timer_fn
Thread running inet_csk_route_req() owns a reference on the request socket, so we have the guarantee ireq->ireq_opt wont be changed or freed.
lockdep can enforce this invariant for us.
Fixes: c92e8c02fe66 ("tcp/dccp: fix ireq->opt races") Signed-off-by: Eric Dumazet edumazet@google.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/ipv4/inet_connection_sock.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/net/ipv4/inet_connection_sock.c +++ b/net/ipv4/inet_connection_sock.c @@ -415,7 +415,8 @@ struct dst_entry *inet_csk_route_req(con struct ip_options_rcu *opt; struct rtable *rt;
- opt = rcu_dereference(ireq->ireq_opt); + opt = rcu_dereference_protected(ireq->ireq_opt, + atomic_read(&req->rsk_refcnt) > 0); flowi4_init_output(fl4, ireq->ir_iif, ireq->ir_mark, RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE, sk->sk_protocol, inet_sk_flowi_flags(sk),