From nobody Wed Apr 1 11:13:38 2026 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C17AD426EAA for ; Tue, 31 Mar 2026 16:50:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774975854; cv=none; b=KLP0JhqCimXnTceMAf0RgIbTKkckxcF9gMGIwwns1DkL1t9IWpGFsUWlkku1Qf37Jpb5pUZ4tvvle9F+l6bxYVeM1KLbypbubcX5BNOeWjU2mr6AH85oRy3sCSyfvbTSaPFnKfvF+Zh3bvH5a8iUtko7HEHeFBoqTrEIouqXDi4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774975854; c=relaxed/simple; bh=ZyVbSFWmIU7uDytGreLAcaUQEeqjF+w10rnvomXCMqY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=am1q8dUqIsyOvTZ+0Jvhy5Eqv1K3YmiFWRsB2H68X32NJh+kW6qJoLt03j1Ae2ES2AER4GCeUMeqbYTx0VZsqEiHz7ndw2m021Q5zdTsXpLQRaqipwblMDm1QvDSSmhP6dzezel/1SUoSNuLhujmTh9qmEM/8/eJIZuwaF3bzmo= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=VI2JNtc8; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="VI2JNtc8" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1774975852; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Smk7qzOFqWQpEDvgIootgLUtedzkckjlb8UVNDwFioI=; b=VI2JNtc8TZ1eqfuk2be86jIBfWjoEWNTDQOQu42l1iwjz7IHUB55w8HCSuBaqtSjOfasAM Jr9VO8az3s2OtIouP/zF2FNOht/o3b2hnQaq3qiK45jwgVZAxpJ8nr0lKxuF0UnsLMJqq1 urlonkBbZQv3U0NckzbIuoZEfn9MjWk= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-516-koyYgahXNDmXFd0erQnMjg-1; Tue, 31 Mar 2026 12:50:47 -0400 X-MC-Unique: koyYgahXNDmXFd0erQnMjg-1 X-Mimecast-MFC-AGG-ID: koyYgahXNDmXFd0erQnMjg_1774975845 Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id D2E681800371; Tue, 31 Mar 2026 16:50:43 +0000 (UTC) Received: from llong-thinkpadp16vgen1.westford.csb (unknown [10.22.80.26]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id AE87B180036E; Tue, 31 Mar 2026 16:50:40 +0000 (UTC) From: Waiman Long To: Simon Horman , Julian Anastasov , "David S. Miller" , David Ahern , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Pablo Neira Ayuso , Florian Westphal , Phil Sutter , Frederic Weisbecker , Chen Ridong , Phil Auld Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org, lvs-devel@vger.kernel.org, netfilter-devel@vger.kernel.org, coreteam@netfilter.org, sheviks , Waiman Long Subject: [PATCH-next v2 2/2] ipvs: Guard access of HK_TYPE_KTHREAD cpumask with RCU Date: Tue, 31 Mar 2026 12:50:15 -0400 Message-ID: <20260331165015.2777765-3-longman@redhat.com> In-Reply-To: <20260331165015.2777765-1-longman@redhat.com> References: <20260331165015.2777765-1-longman@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 Content-Type: text/plain; charset="utf-8" The ip_vs_ctl.c file and the associated ip_vs.h file are the only places in the kernel where HK_TYPE_KTHREAD cpumask is being retrieved and used. Now that HK_TYPE_KTHREAD/HK_TYPE_DOMAIN cpumask can be changed at run time. We need to use RCU to guard access to this cpumask to avoid a potential UAF problem as the returned cpumask may be freed before it is being used. We can replace HK_TYPE_KTHREAD by HK_TYPE_DOMAIN as they are aliases of each other, but keeping the HK_TYPE_KTHREAD name can highlight the fact that it is the kthread initiated by ipvs that is being controlled. Signed-off-by: Waiman Long --- include/net/ip_vs.h | 20 ++++++++++++++++---- net/netfilter/ipvs/ip_vs_ctl.c | 13 ++++++++----- 2 files changed, 24 insertions(+), 9 deletions(-) diff --git a/include/net/ip_vs.h b/include/net/ip_vs.h index 72d325c81313..7bda92fd3fe6 100644 --- a/include/net/ip_vs.h +++ b/include/net/ip_vs.h @@ -1411,7 +1411,7 @@ static inline int sysctl_run_estimation(struct netns_= ipvs *ipvs) return ipvs->sysctl_run_estimation; } =20 -static inline const struct cpumask *sysctl_est_cpulist(struct netns_ipvs *= ipvs) +static inline const struct cpumask *__sysctl_est_cpulist(struct netns_ipvs= *ipvs) { if (ipvs->est_cpulist_valid) return ipvs->sysctl_est_cpulist; @@ -1529,7 +1529,7 @@ static inline int sysctl_run_estimation(struct netns_= ipvs *ipvs) return 1; } =20 -static inline const struct cpumask *sysctl_est_cpulist(struct netns_ipvs *= ipvs) +static inline const struct cpumask *__sysctl_est_cpulist(struct netns_ipvs= *ipvs) { return housekeeping_cpumask(HK_TYPE_KTHREAD); } @@ -1564,6 +1564,18 @@ static inline int sysctl_svc_lfactor(struct netns_ip= vs *ipvs) return READ_ONCE(ipvs->sysctl_svc_lfactor); } =20 +static inline bool sysctl_est_cpulist_empty(struct netns_ipvs *ipvs) +{ + guard(rcu)(); + return cpumask_empty(__sysctl_est_cpulist(ipvs)); +} + +static inline unsigned int sysctl_est_cpulist_weight(struct netns_ipvs *ip= vs) +{ + guard(rcu)(); + return cpumask_weight(__sysctl_est_cpulist(ipvs)); +} + /* IPVS core functions * (from ip_vs_core.c) */ @@ -1895,7 +1907,7 @@ static inline void ip_vs_est_stopped_recalc(struct ne= tns_ipvs *ipvs) /* Stop tasks while cpulist is empty or if disabled with flag */ ipvs->est_stopped =3D !sysctl_run_estimation(ipvs) || (ipvs->est_cpulist_valid && - cpumask_empty(sysctl_est_cpulist(ipvs))); + sysctl_est_cpulist_empty(ipvs)); #endif } =20 @@ -1911,7 +1923,7 @@ static inline bool ip_vs_est_stopped(struct netns_ipv= s *ipvs) static inline int ip_vs_est_max_threads(struct netns_ipvs *ipvs) { unsigned int limit =3D IPVS_EST_CPU_KTHREADS * - cpumask_weight(sysctl_est_cpulist(ipvs)); + sysctl_est_cpulist_weight(ipvs); =20 return max(1U, limit); } diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c index 032425025d88..e253a1ceef48 100644 --- a/net/netfilter/ipvs/ip_vs_ctl.c +++ b/net/netfilter/ipvs/ip_vs_ctl.c @@ -2338,11 +2338,14 @@ static int ipvs_proc_est_cpumask_get(const struct c= tl_table *table, =20 mutex_lock(&ipvs->est_mutex); =20 - if (ipvs->est_cpulist_valid) - mask =3D *valp; - else - mask =3D (struct cpumask *)housekeeping_cpumask(HK_TYPE_KTHREAD); - ret =3D scnprintf(buffer, size, "%*pbl\n", cpumask_pr_args(mask)); + /* HK_TYPE_KTHREAD cpumask needs RCU protection */ + scoped_guard(rcu) { + if (ipvs->est_cpulist_valid) + mask =3D *valp; + else + mask =3D (struct cpumask *)housekeeping_cpumask(HK_TYPE_KTHREAD); + ret =3D scnprintf(buffer, size, "%*pbl\n", cpumask_pr_args(mask)); + } =20 mutex_unlock(&ipvs->est_mutex); =20 --=20 2.53.0