This is a note to let you know that I've just added the patch titled
tcp: fix race in tcp_v6_syn_recv_sock()
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
tcp-fix-race-in-tcp_v6_syn_recv_sock.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit a2183de305f2f8aca4c26e94d2796888dd3b35e4
Author: Eric Dumazet <edumazet@xxxxxxxxxx>
Date: Thu Jun 6 15:46:51 2024 +0000
tcp: fix race in tcp_v6_syn_recv_sock()
[ 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@xxxxxxxxxx>
Reviewed-by: Simon Horman <horms@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
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;
