tcp/dccp: fix ireq->pktopts race
IPv6 request sockets store a pointer to skb containing the SYN packet
to be able to transfer it to full blown socket when 3WHS is done
(ireq->pktopts -> np->pktoptions)
As explained in commit 5e0724d027f0 ("tcp/dccp: fix hashdance race for
passive sessions"), we must transfer the skb only if we won the
hashdance race, if multiple cpus receive the 'ack' packet completing
3WHS at the same time.
Fixes: e994b2f0fb92 ("tcp: do not lock listener to process SYN packets")
Fixes: 079096f103fa ("tcp/dccp: install syn_recv requests into ehash table")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 714bc5a..ea2f4d5 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1084,16 +1084,7 @@
/* Clone RX bits */
newnp->rxopt.all = np->rxopt.all;
- /* Clone pktoptions received with SYN */
newnp->pktoptions = NULL;
- if (ireq->pktopts) {
- newnp->pktoptions = skb_clone(ireq->pktopts,
- sk_gfp_atomic(sk, GFP_ATOMIC));
- consume_skb(ireq->pktopts);
- ireq->pktopts = NULL;
- if (newnp->pktoptions)
- skb_set_owner_r(newnp->pktoptions, newsk);
- }
newnp->opt = NULL;
newnp->mcast_oif = tcp_v6_iif(skb);
newnp->mcast_hops = ipv6_hdr(skb)->hop_limit;
@@ -1149,6 +1140,15 @@
goto out;
}
*own_req = inet_ehash_nolisten(newsk, req_to_sk(req_unhash));
+ /* Clone pktoptions received with SYN, if we own the req */
+ if (*own_req && ireq->pktopts) {
+ newnp->pktoptions = skb_clone(ireq->pktopts,
+ sk_gfp_atomic(sk, GFP_ATOMIC));
+ consume_skb(ireq->pktopts);
+ ireq->pktopts = NULL;
+ if (newnp->pktoptions)
+ skb_set_owner_r(newnp->pktoptions, newsk);
+ }
return newsk;