From: Eric Dumazet Date: Thu, 6 Jun 2024 15:46:51 +0000 (+0000) Subject: tcp: fix race in tcp_v6_syn_recv_sock() X-Git-Tag: v6.10-rc4~26^2~18 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=d37fe4255abe8e7b419b90c5847e8ec2b8debb08;p=thirdparty%2Fkernel%2Flinux.git tcp: fix race in tcp_v6_syn_recv_sock() 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 Reviewed-by: Simon Horman Signed-off-by: David S. Miller --- diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index 8c577b651bfcd..729faf8bd366a 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;