From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 DDC7747D443; Thu, 20 Aug 2026 16:31:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787243514; cv=none; b=k2vrc2nWVPZSG4G02q9978prPHNXCKqBzHoeW8wEzvXmrEDHULKnB699zA5SOqn9BvXqIn9BAs1BMffxAUN7XBRcioPSYc1fq8saoDVvBaCIkE2aKMB3EbgyzPA4lNY1K3u7pvn2l7OYzfmDXB814aD/ihr7i95+zzC94VRj9xM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787243514; c=relaxed/simple; bh=3WJr04acrhhHXMjplak1tYMIgU8frAg0DhAtrZaVqhE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=sUtEsmMzDT0si+4zDxcMEUZKL9oDzUCM1/i3WvDVdh5sP4Ld+w85ETn1xeQpYf7/GMFWBk5K4up5IirYccE+9cbSIy8tq9B690xQSdURMdJwpndbPwoosSqV/GVVkP34WHkUZ5oo3MxLgWB2Fc02TRBCf+df/zGmOLx7so3gXhk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=lgO5783M; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="lgO5783M" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 455AB1F000E9; Thu, 20 Aug 2026 16:31:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1787243512; bh=wsdAivJDmCfmtuS1ontahTQEigS9WKyV/8Y1tdCu23I=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=lgO5783Mvz24mWpL4YFPjr3Qvo7j1ZckZX2AkDcpdtNHIspCF//qIc7zicS5b74YB ijqy2wBt7W7RK++C9zAnKDPlYpIjKglUNd/Z8/+UlWoATIbl2bItCq+a32eTP2Jyjn x/j2l5gi4aLYQzTLUxkhsQTBXZXUmE+BCaaYM2qQ= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Eric Dumazet , Kuniyuki Iwashima , Jakub Kicinski , Sasha Levin Subject: [PATCH 5.15 081/272] net: dst: annotate data-races around dst->output Date: Thu, 20 Aug 2026 16:54:25 +0200 Message-ID: <20260820145233.707162873@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260820145231.229664293@linuxfoundation.org> References: <20260820145231.229664293@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet [ Upstream commit 2dce8c52a98995c4719def6f88629ab1581c0b82 ] dst_dev_put() can overwrite dst->output while other cpus might read this field (for instance from dst_output()) Add READ_ONCE()/WRITE_ONCE() annotations to suppress potential issues. We will likely need RCU protection in the future. Fixes: 4a6ce2b6f2ec ("net: introduce a new function dst_dev_put()") Signed-off-by: Eric Dumazet Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250630121934.3399505-6-edumazet@google.com Signed-off-by: Jakub Kicinski Stable-dep-of: c9c9b37f8c55 ("netfilter: nf_queue: pin bridge device while NFQUEUE holds fake dst") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- include/net/dst.h | 2 +- include/net/lwtunnel.h | 4 ++-- net/core/dst.c | 2 +- net/ipv4/route.c | 2 +- 4 files changed, 5 insertions(+), 5 deletions(-) --- a/include/net/dst.h +++ b/include/net/dst.h @@ -449,7 +449,7 @@ INDIRECT_CALLABLE_DECLARE(int ip_output( /* Output packet to network from transport. */ static inline int dst_output(struct net *net, struct sock *sk, struct sk_buff *skb) { - return INDIRECT_CALL_INET(skb_dst(skb)->output, + return INDIRECT_CALL_INET(READ_ONCE(skb_dst(skb)->output), ip6_output, ip_output, net, sk, skb); } --- a/include/net/lwtunnel.h +++ b/include/net/lwtunnel.h @@ -138,8 +138,8 @@ int bpf_lwt_push_ip_encap(struct sk_buff static inline void lwtunnel_set_redirect(struct dst_entry *dst) { if (lwtunnel_output_redirect(dst->lwtstate)) { - dst->lwtstate->orig_output = dst->output; - dst->output = lwtunnel_output; + dst->lwtstate->orig_output = READ_ONCE(dst->output); + WRITE_ONCE(dst->output, lwtunnel_output); } if (lwtunnel_input_redirect(dst->lwtstate)) { dst->lwtstate->orig_input = READ_ONCE(dst->input); --- a/net/core/dst.c +++ b/net/core/dst.c @@ -150,7 +150,7 @@ void dst_dev_put(struct dst_entry *dst) if (dst->ops->ifdown) dst->ops->ifdown(dst, dev, true); WRITE_ONCE(dst->input, dst_discard); - dst->output = dst_discard_out; + WRITE_ONCE(dst->output, dst_discard_out); dst->dev = blackhole_netdev; dev_hold(dst->dev); dev_put(dev); --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -1733,7 +1733,7 @@ struct rtable *rt_dst_clone(struct net_d INIT_LIST_HEAD(&new_rt->rt_uncached); new_rt->dst.input = READ_ONCE(rt->dst.input); - new_rt->dst.output = rt->dst.output; + new_rt->dst.output = READ_ONCE(rt->dst.output); new_rt->dst.error = rt->dst.error; new_rt->dst.lastuse = jiffies; new_rt->dst.lwtstate = lwtstate_get(rt->dst.lwtstate);