From ce1050089c969b96c797118f9cb0cf5a421ddc69 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Fri, 30 Oct 2015 09:46:12 -0700 Subject: [PATCH] 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 Signed-off-by: David S. Miller --- net/dccp/ipv6.c | 16 ++++++++-------- net/ipv6/tcp_ipv6.c | 18 +++++++++--------- 2 files changed, 17 insertions(+), 17 deletions(-) diff --git a/net/dccp/ipv6.c b/net/dccp/ipv6.c index ef4e48c..db5fc24 100644 --- a/net/dccp/ipv6.c +++ b/net/dccp/ipv6.c @@ -477,15 +477,7 @@ static struct sock *dccp_v6_request_recv_sock(const struct sock *sk, /* Clone RX bits */ newnp->rxopt.all = np->rxopt.all; - /* Clone pktoptions received with SYN */ newnp->pktoptions = NULL; - if (ireq->pktopts != NULL) { - newnp->pktoptions = skb_clone(ireq->pktopts, 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 = inet6_iif(skb); newnp->mcast_hops = ipv6_hdr(skb)->hop_limit; @@ -515,6 +507,14 @@ static struct sock *dccp_v6_request_recv_sock(const struct sock *sk, 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, GFP_ATOMIC); + consume_skb(ireq->pktopts); + ireq->pktopts = NULL; + if (newnp->pktoptions) + skb_set_owner_r(newnp->pktoptions, newsk); + } return newsk; 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 @@ static struct sock *tcp_v6_syn_recv_sock(const struct sock *sk, struct sk_buff * /* 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 @@ static struct sock *tcp_v6_syn_recv_sock(const struct sock *sk, struct sk_buff * 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; -- 2.7.4