From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794591174; b=KGfPMga0GpiOXvaL+sn6ejOxCxSiNTGQ0/Vatf/sCzaB2rEUqdCL/EpmKgr5RLaebu85 oewRxN4yRunEcIqn2CbDvlHE1jt4/gNpAfAfMCWk12n2cm2Vzm/nk5Bc5L9YyLZMYxsXX mHuwDSbGCVWH16I+4H0ZyyMbOpB1i760sNzL7kYVnOnHksUGyb3DOCAE0caSypcsaKgC3 V0Zz76ngVwbW/XlXKaWa1Xj/m1ki0E9yuzd7ysh+iIhxNqb2jFXTrWKzS6hcV5UNJIzZw dnMoEvt35uRNLs1ne5RG58vleUlGAoaPsSs1/fejIMqXZmol3bveN2ksXh9yitSaVmw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794591174; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=ew9kQy21AQnHujJWQplZpaD0ZqA5fYINdQbSWlj4u6I=; b=44lNkxgpcM+eWtPmkq7GMonLAsFVtmVFgViqIjtp/iv0uy+gKXUzsDLXHMxVQGzAy4Za jVhxIuUnQ6oJOgiYYm5J/AW1iRrvSUnzyMRD9v+d2IhKQc7ZmzNWBODRQUMDGHEH2QbRr BqoKATTv1bEsUlM4NsZ+AlkZ0S8leV+9YepTbT+Myawu5G9cZcN/V+Q365n1v5gxxm5hv NRjL6zBSVx/cWQUQn+UTyy3gw79jWpopsC4L7x3Bo7yQjUiTFUxhGQWjGkGuUAMNFRf2B yznGF8jEobFcD+YR7EZewBt6MEzfrOo2kxzBpH4RIzs45xp3TNql4MnD2IgwtGQVF5Q== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=HkITTDQb; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8CC9E6073FE1; Fri, 13 Nov 2026 17:32:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=HkITTDQb Received: by smtp.kernel.org (Postfix) with ESMTPSA id 388C11F000C8; Fri, 13 Nov 2026 17:32:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1794591174; bh=ew9kQy21AQnHujJWQplZpaD0ZqA5fYINdQbSWlj4u6I=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=HkITTDQb3DRwI+xxfFHImW82ExaXPv9MqspwegJRY9vdYLcUB/SsALuL9L/s+62gO SglduECEpdom/XVDYFstAY8ImtCMMb1sfnT0bgkWaw3etc9+JMX0x5YdkBpEvbKhY2 yLQ2uzDah81uc/5usI+Y0k0l8wTj72p0qHCYr3tY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Hyunwoo Kim , Kuniyuki Iwashima , Paolo Abeni , Sasha Levin Subject: [PATCH 6.12 314/670] net: restore refcount ordering for lockless socket access Date: Fri, 13 Nov 2026 10:47:58 -0500 Message-ID: <20261113153822.542473891@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261113153811.177190860@linuxfoundation.org> References: <20261113153811.177190860@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Hyunwoo Kim [ Upstream commit 5b5d8f351dd96f56a58bb516a80e2d4d742fe4e2 ] Before commit fb041bb7c0a9 ("locking/refcount: Consolidate implementations of refcount_t"), default builds implemented refcount_inc_not_zero() using atomic_add_unless(), which provided full memory ordering on success. The commit removed that ordering on weakly ordered architectures, allowing accesses after a successful reference acquisition to be reordered before it. Use refcount_inc_not_zero_acquire() in the IPv4 and IPv6 established lookups and in inet_twsk_purge(), where the socket is validated again after taking a reference. bpf_sk_assign() can receive a socket pointer obtained through BTF without a reference. Use acquire ordering when it takes its own reference for a refcounted socket. Use refcount_set_release() when setting refcounts in the SYN cookie, TCP Fast Open, request migration, and TIME_WAIT paths. Keep the existing TIME_WAIT smp_wmb(), which separately orders the refcount store before ehash publication. Fixes: fb041bb7c0a9 ("locking/refcount: Consolidate implementations of refcount_t") Fixes: 27e5203bd9c5 ("bpf: Change bpf_sk_assign to accept ARG_PTR_TO_BTF_ID_SOCK_COMMON") Cc: stable@vger.kernel.org Signed-off-by: Hyunwoo Kim Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20261029214219.1035176-3-imv4bel@gmail.com Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin --- net/core/filter.c | 2 +- net/ipv4/inet_connection_sock.c | 6 +++--- net/ipv4/inet_hashtables.c | 2 +- net/ipv4/inet_timewait_sock.c | 4 ++-- net/ipv4/syncookies.c | 2 +- net/ipv4/tcp_fastopen.c | 2 +- net/ipv6/inet6_hashtables.c | 2 +- 7 files changed, 10 insertions(+), 10 deletions(-) diff --git a/net/core/filter.c b/net/core/filter.c index 5ec9954b94542..2d6e2f772a600 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -7625,7 +7625,7 @@ BPF_CALL_3(bpf_sk_assign, struct sk_buff *, skb, struct sock *, sk, u64, flags) if (sk_unhashed(sk)) return -EOPNOTSUPP; if (sk_is_refcounted(sk) && - unlikely(!refcount_inc_not_zero(&sk->sk_refcnt))) + unlikely(!refcount_inc_not_zero_acquire(&sk->sk_refcnt))) return -ENOENT; skb_orphan(skb); diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c index 2cb125bbfb9db..61fbcaa913b35 100644 --- a/net/ipv4/inet_connection_sock.c +++ b/net/ipv4/inet_connection_sock.c @@ -1105,8 +1105,8 @@ static void reqsk_timer_handler(struct timer_list *t) * hold another count to prevent use-after-free and * call reqsk_put() just before return. */ - refcount_set(&nreq->rsk_refcnt, 2 + 1); timer_setup(&nreq->rsk_timer, reqsk_timer_handler, TIMER_PINNED); + refcount_set_release(&nreq->rsk_refcnt, 2 + 1); reqsk_queue_migrated(&inet_csk(nsk)->icsk_accept_queue, req); req = nreq; @@ -1465,7 +1465,7 @@ struct sock *inet_csk_complete_hashdance(struct sock *sk, struct sock *child, goto child_put; } - refcount_set(&nreq->rsk_refcnt, 1); + refcount_set_release(&nreq->rsk_refcnt, 1); if (inet_csk_reqsk_queue_add(sk, nreq, child)) { __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMIGRATEREQSUCCESS); reqsk_migrate_reset(req); @@ -1519,7 +1519,7 @@ void inet_csk_listen_stop(struct sock *sk) if (nsk) { nreq = inet_reqsk_clone(req, nsk); if (nreq) { - refcount_set(&nreq->rsk_refcnt, 1); + refcount_set_release(&nreq->rsk_refcnt, 1); rcu_read_lock(); if (inet_csk_reqsk_queue_add(nsk, nreq, child)) { diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c index e8adf8530596c..e7b312f7cd98f 100644 --- a/net/ipv4/inet_hashtables.c +++ b/net/ipv4/inet_hashtables.c @@ -510,7 +510,7 @@ struct sock *__inet_lookup_established(const struct net *net, if (sk->sk_hash != hash) continue; if (likely(inet_match(net, sk, acookie, ports, dif, sdif))) { - if (unlikely(!refcount_inc_not_zero(&sk->sk_refcnt))) + if (unlikely(!refcount_inc_not_zero_acquire(&sk->sk_refcnt))) goto out; if (unlikely(hlist_nulls_unhashed_lockless(&sk->sk_nulls_node) || !inet_match(net, sk, acookie, ports, dif, diff --git a/net/ipv4/inet_timewait_sock.c b/net/ipv4/inet_timewait_sock.c index 74b84ac418e93..e34deccdcb30f 100644 --- a/net/ipv4/inet_timewait_sock.c +++ b/net/ipv4/inet_timewait_sock.c @@ -139,7 +139,7 @@ void inet_twsk_hashdance_schedule(struct inet_timewait_sock *tw, * Also note that after this point, we lost our implicit reference * so we are not allowed to use tw anymore. */ - refcount_set(&tw->tw_refcnt, 3); + refcount_set_release(&tw->tw_refcnt, 3); /* Ensure tw_refcnt has been set before tw is published. * smp_wmb() provides the necessary memory barrier to enforce this @@ -324,7 +324,7 @@ void inet_twsk_purge(struct inet_hashinfo *hashinfo) if (refcount_read(&sock_net(sk)->ns.count)) continue; - if (unlikely(!refcount_inc_not_zero(&sk->sk_refcnt))) + if (unlikely(!refcount_inc_not_zero_acquire(&sk->sk_refcnt))) continue; if (refcount_read(&sock_net(sk)->ns.count)) { diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c index 16361ce3e8062..43cf33f282c15 100644 --- a/net/ipv4/syncookies.c +++ b/net/ipv4/syncookies.c @@ -204,7 +204,7 @@ struct sock *tcp_get_cookie_sock(struct sock *sk, struct sk_buff *skb, child = icsk->icsk_af_ops->syn_recv_sock(sk, skb, req, dst, NULL, &own_req, NULL); if (child) { - refcount_set(&req->rsk_refcnt, 1); + refcount_set_release(&req->rsk_refcnt, 1); sock_rps_save_rxhash(child, skb); if (rsk_drop_req(req)) { diff --git a/net/ipv4/tcp_fastopen.c b/net/ipv4/tcp_fastopen.c index 5378ef3b6ab53..fbcd7d8c8d99e 100644 --- a/net/ipv4/tcp_fastopen.c +++ b/net/ipv4/tcp_fastopen.c @@ -278,7 +278,7 @@ static struct sock *tcp_fastopen_create_child(struct sock *sk, inet_csk_reset_xmit_timer(child, ICSK_TIME_RETRANS, req->timeout, TCP_RTO_MAX); - refcount_set(&req->rsk_refcnt, 2); + refcount_set_release(&req->rsk_refcnt, 2); sk_mark_napi_id_set(child, skb); diff --git a/net/ipv6/inet6_hashtables.c b/net/ipv6/inet6_hashtables.c index 70633fed6e6af..dee00ba290f69 100644 --- a/net/ipv6/inet6_hashtables.c +++ b/net/ipv6/inet6_hashtables.c @@ -71,7 +71,7 @@ struct sock *__inet6_lookup_established(const struct net *net, continue; if (!inet6_match(net, sk, saddr, daddr, ports, dif, sdif)) continue; - if (unlikely(!refcount_inc_not_zero(&sk->sk_refcnt))) + if (unlikely(!refcount_inc_not_zero_acquire(&sk->sk_refcnt))) goto out; if (unlikely(hlist_nulls_unhashed_lockless(&sk->sk_nulls_node) || -- 2.53.0