From: Eric Dumazet <edumazet@google•com>
To: "David S . Miller" <davem@davemloft•net>,
Jakub Kicinski <kuba@kernel•org>,
Paolo Abeni <pabeni@redhat•com>
Cc: netdev@vger•kernel.org, Neal Cardwell <ncardwell@google•com>,
eric.dumazet@gmail•com, Eric Dumazet <edumazet@google•com>
Subject: [PATCH net] tcp: fix race in tcp_v6_syn_recv_sock()
Date: Thu, 6 Jun 2024 15:46:51 +0000 [thread overview]
Message-ID: <20240606154652.360331-1-edumazet@google.com> (raw)
tcp_v6_syn_recv_sock() calls ip6_dst_store() before
inet_sk(newsk)->pinet6 has been set up.
This means ip6_dst_store() writes over the parent (listener)
np->dst_cookie.
This is racy because multiple threads could share the same
parent and their final np->dst_cookie could be wrong.
Move ip6_dst_store() call after inet_sk(newsk)->pinet6
has been changed and after the copy of parent ipv6_pinfo.
Fixes: e994b2f0fb92 ("tcp: do not lock listener to process SYN packets")
Signed-off-by: Eric Dumazet <edumazet@google•com>
---
net/ipv6/tcp_ipv6.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 8c577b651bfcd2f94b45e339ed4a2b47e93ff17a..729faf8bd366ad25d093a4ae931fb46ebd45b79c 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1439,7 +1439,6 @@ static struct sock *tcp_v6_syn_recv_sock(const struct sock *sk, struct sk_buff *
*/
newsk->sk_gso_type = SKB_GSO_TCPV6;
- ip6_dst_store(newsk, dst, NULL, NULL);
inet6_sk_rx_dst_set(newsk, skb);
inet_sk(newsk)->pinet6 = tcp_inet6_sk(newsk);
@@ -1450,6 +1449,8 @@ static struct sock *tcp_v6_syn_recv_sock(const struct sock *sk, struct sk_buff *
memcpy(newnp, np, sizeof(struct ipv6_pinfo));
+ ip6_dst_store(newsk, dst, NULL, NULL);
+
newsk->sk_v6_daddr = ireq->ir_v6_rmt_addr;
newnp->saddr = ireq->ir_v6_loc_addr;
newsk->sk_v6_rcv_saddr = ireq->ir_v6_loc_addr;
--
2.45.1.467.gbab1589fc0-goog
next reply other threads:[~2024-06-06 15:46 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-06-06 15:46 Eric Dumazet [this message]
2024-06-08 13:25 ` [PATCH net] tcp: fix race in tcp_v6_syn_recv_sock() Simon Horman
2024-06-10 15:30 ` David Ahern
2024-06-10 12:20 ` patchwork-bot+netdevbpf
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