From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 E494F3BD64F; Mon, 23 Mar 2026 16:15:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774282526; cv=none; b=PCIvTh2qw+jWQPtPeI3aL+Zeo65afrzhF7RhFBV1DBta/2znT/jPbRZAcZt0sDGIb7BvDrKaduVvC2U8DNlVMYv1PoHfw3EPodENwyTcziLAUfqi/kyqKmnkye0Us1ptY1MdRUKNPnrm3/HDfkf4l0Tlc6N8jQ9cvARoyWHfcvk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774282526; c=relaxed/simple; bh=p+2BwaKYeFZUc5WfAjoV3TG1bgKcvmhJL0YWuPfOyzU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=r7GNFuqqea85dZbGUdmkmjSJGTTe0koKoi0NlBIaFdBHbLPgln2n/1rbSiBRPXUyX411Jqr3DhCXpSwZepsl99n9VSLFXY9zJ1EIsRfyqLv2uC5VOiW/j/bC1EtInKyYHNevaoF7dqmd7r6gp+6MN/dmkHIsuEebYW55k16Ta04= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=m8gRooyQ; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="m8gRooyQ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 75BE2C2BCB0; Mon, 23 Mar 2026 16:15:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1774282525; bh=p+2BwaKYeFZUc5WfAjoV3TG1bgKcvmhJL0YWuPfOyzU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=m8gRooyQU0iJhe5K6S0oaVYBkh68T6iX1ASYeVMMA8ZR/Og1eFOrcrUiJlKxFoBgm gyfvV1m13rXGUViaea6dGZqmOmEUZXnFhwOBnBQ2IOBzDFbkShsTdqhVjbDf6rj9g6 u1dEnipsw8Tuik1Ymt0MfkX9L52+Ud6yq7AGCqQs= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, GangMin Kim , Victor Nogueira , Jamal Hadi Salim , Jakub Kicinski Subject: [PATCH 6.1 144/481] net/sched: Only allow act_ct to bind to clsact/ingress qdiscs and shared blocks Date: Mon, 23 Mar 2026 14:42:06 +0100 Message-ID: <20260323134528.765856589@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260323134525.256603107@linuxfoundation.org> References: <20260323134525.256603107@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Victor Nogueira commit 11cb63b0d1a0685e0831ae3c77223e002ef18189 upstream. As Paolo said earlier [1]: "Since the blamed commit below, classify can return TC_ACT_CONSUMED while the current skb being held by the defragmentation engine. As reported by GangMin Kim, if such packet is that may cause a UaF when the defrag engine later on tries to tuch again such packet." act_ct was never meant to be used in the egress path, however some users are attaching it to egress today [2]. Attempting to reach a middle ground, we noticed that, while most qdiscs are not handling TC_ACT_CONSUMED, clsact/ingress qdiscs are. With that in mind, we address the issue by only allowing act_ct to bind to clsact/ingress qdiscs and shared blocks. That way it's still possible to attach act_ct to egress (albeit only with clsact). [1] https://lore.kernel.org/netdev/674b8cbfc385c6f37fb29a1de08d8fe5c2b0fbee.1771321118.git.pabeni@redhat.com/ [2] https://lore.kernel.org/netdev/cc6bfb4a-4a2b-42d8-b9ce-7ef6644fb22b@ovn.org/ Reported-by: GangMin Kim Fixes: 3f14b377d01d ("net/sched: act_ct: fix skb leak and crash on ooo frags") CC: stable@vger.kernel.org Signed-off-by: Victor Nogueira Acked-by: Jamal Hadi Salim Link: https://patch.msgid.link/20260225134349.1287037-1-victor@mojatatu.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- include/net/act_api.h | 1 + net/sched/act_ct.c | 6 ++++++ net/sched/cls_api.c | 7 +++++++ 3 files changed, 14 insertions(+) --- a/include/net/act_api.h +++ b/include/net/act_api.h @@ -67,6 +67,7 @@ struct tc_action { #define TCA_ACT_FLAGS_BIND (1U << (TCA_ACT_FLAGS_USER_BITS + 1)) #define TCA_ACT_FLAGS_REPLACE (1U << (TCA_ACT_FLAGS_USER_BITS + 2)) #define TCA_ACT_FLAGS_NO_RTNL (1U << (TCA_ACT_FLAGS_USER_BITS + 3)) +#define TCA_ACT_FLAGS_AT_INGRESS_OR_CLSACT (1U << (TCA_ACT_FLAGS_USER_BITS + 5)) /* Update lastuse only if needed, to avoid dirtying a cache line. * We use a temp variable to avoid fetching jiffies twice. --- a/net/sched/act_ct.c +++ b/net/sched/act_ct.c @@ -1440,6 +1440,12 @@ static int tcf_ct_init(struct net *net, return -EINVAL; } + if (bind && !(flags & TCA_ACT_FLAGS_AT_INGRESS_OR_CLSACT)) { + NL_SET_ERR_MSG_MOD(extack, + "Attaching ct to a non ingress/clsact qdisc is unsupported"); + return -EOPNOTSUPP; + } + err = nla_parse_nested(tb, TCA_CT_MAX, nla, ct_policy, extack); if (err < 0) return err; --- a/net/sched/cls_api.c +++ b/net/sched/cls_api.c @@ -1993,6 +1993,11 @@ static void tfilter_put(struct tcf_proto tp->ops->put(tp, fh); } +static bool is_ingress_or_clsact(struct tcf_block *block, struct Qdisc *q) +{ + return tcf_block_shared(block) || (q && !!(q->flags & TCQ_F_INGRESS)); +} + static int tc_new_tfilter(struct sk_buff *skb, struct nlmsghdr *n, struct netlink_ext_ack *extack) { @@ -2184,6 +2189,8 @@ replay: flags |= TCA_ACT_FLAGS_REPLACE; if (!rtnl_held) flags |= TCA_ACT_FLAGS_NO_RTNL; + if (is_ingress_or_clsact(block, q)) + flags |= TCA_ACT_FLAGS_AT_INGRESS_OR_CLSACT; err = tp->ops->change(net, skb, tp, cl, t->tcm_handle, tca, &fh, flags, extack); if (err == 0) {