5.4-stable review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet edumazet@google.com
[ Upstream commit d37fe4255abe8e7b419b90c5847e8ec2b8debb08 ]
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 Reviewed-by: Simon Horman horms@kernel.org Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- 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 7cb622d300aa2..c5efbfe2a2c4a 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -1228,7 +1228,6 @@ 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); @@ -1239,6 +1238,8 @@ 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;