Commit 805c4bc0 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller

tcp: fix req->saved_syn race

For the reasons explained in commit ce105008 ("tcp/dccp: fix
ireq->pktopts race"), we need to make sure we do not access
req->saved_syn unless we own the request sock.

This fixes races for listeners using TCP_SAVE_SYN option.

Fixes: e994b2f0 ("tcp: do not lock listener to process SYN packets")
Fixes: 079096f1 ("tcp/dccp: install syn_recv requests into ehash table")
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Reported-by: default avatarYing Cai <ycai@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 428ad1bc
......@@ -397,6 +397,13 @@ static inline void fastopen_queue_tune(struct sock *sk, int backlog)
queue->fastopenq.max_qlen = min_t(unsigned int, backlog, somaxconn);
}
static inline void tcp_move_syn(struct tcp_sock *tp,
struct request_sock *req)
{
tp->saved_syn = req->saved_syn;
req->saved_syn = NULL;
}
static inline void tcp_saved_syn_free(struct tcp_sock *tp)
{
kfree(tp->saved_syn);
......
......@@ -1326,6 +1326,8 @@ struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb,
if (__inet_inherit_port(sk, newsk) < 0)
goto put_and_exit;
*own_req = inet_ehash_nolisten(newsk, req_to_sk(req_unhash));
if (*own_req)
tcp_move_syn(newtp, req_unhash);
return newsk;
......
......@@ -551,9 +551,6 @@ struct sock *tcp_create_openreq_child(const struct sock *sk,
newtp->rack.mstamp.v64 = 0;
newtp->rack.advanced = 0;
newtp->saved_syn = req->saved_syn;
req->saved_syn = NULL;
TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_PASSIVEOPENS);
}
return newsk;
......
......@@ -1140,8 +1140,11 @@ 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));
if (*own_req) {
tcp_move_syn(newtp, req_unhash);
/* Clone pktoptions received with SYN, if we own the req */
if (*own_req && ireq->pktopts) {
if (ireq->pktopts) {
newnp->pktoptions = skb_clone(ireq->pktopts,
sk_gfp_atomic(sk, GFP_ATOMIC));
consume_skb(ireq->pktopts);
......@@ -1149,6 +1152,7 @@ static struct sock *tcp_v6_syn_recv_sock(const struct sock *sk, struct sk_buff *
if (newnp->pktoptions)
skb_set_owner_r(newnp->pktoptions, newsk);
}
}
return newsk;
......
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