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 4C0532475CF for ; Wed, 30 Sep 2026 00:20:26 +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=1790727627; cv=none; b=P7qWUDlpEPs4c39r9v01nW2eIgtGsdsNg/Ld0ys5SFYPPT78jhisNvh57NGRqk/sFxQ9TIex7np2+QGN7xfHoKKA0sh6DBwFbIetTtxm5fS35KFQAnhve4EBxQ8//vw5xtMejSXmrqivi7evNrXxw8QDNza51F5iNyFFwIQaQdw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790727627; c=relaxed/simple; bh=6YsZXyTFdYmo5kXs5866NXGbcvDiUwg92MB65GM3Hk4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=HZu99N3YJmNrjFXptQ+2U3JvonKEFa1yeNKNj2XwMeGiF/e7IvKg+0ouutwt7Nn+rsnWVCB/bintoFGRN6OH4OXZhVTDpoE7us2H+mLccQMk0WJd3Y44n0gn9neYRiqWr+6CHH5Et6Ljv2yun8L8KyhuhyrunQdC8y97xhP+h1Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=VbyVDIjZ; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="VbyVDIjZ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8C7921F0089A; Wed, 30 Sep 2026 00:20:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790727626; bh=Dzd+C8ujuOjpJwoiqDJxeBK2MHq6ULqXX0Jd/H/cEnA=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=VbyVDIjZAeWLhSUF0OKiKgC7ol4Wh2GOmuroW3WV6Dh0KLh3J9NuXM3ClTmqVoddA tAAYdBX4yx6thZiBrZJl5B2Sl4Q0so9otlrScUBcABtC5mw/KXxnHLUWXofFV8m1ij eYY0oKprtTlGQBhcPQn0RmNRlVSrmWum+y1Gm6z7jvl1zdKLzIRvUBzBKIxud2s0bs sXQf6YbHCCX+NkeQGJ6Nr0kLE2mKs+lMQEB/SO13C/1oJ+AsV41q+HR8Wu4xAcCi+f invCYWQUSkUKfzvyqLnauuKSQwLRxILXxF3wgi7b5gq1UqRJ/CBk+qFvTMiCo2Ykdd GWY2GSQwJlWEw== From: Sasha Levin To: stable@vger.kernel.org Cc: Ilya Maximets , Axel Mierczuk , Aaron Conole , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.18.y 1/2] net: openvswitch: conntrack: avoid modifying shared unconfirmed ct entry Date: Tue, 29 Sep 2026 20:20:23 -0400 Message-ID: <20260930002024.2934218-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026092956-avalanche-oversized-b625@gregkh> References: <2026092956-avalanche-oversized-b625@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Ilya Maximets [ Upstream commit 26b2bd70d22457556e2fa01cbf1192cb1a94d619 ] In a case where skb with an unconfirmed ct entry gets cloned, we may end up committing both but with different sets of extensions. The series of events: 1. The first clone wants to commit and runs the helpers wiring up the extension pointer into the expectation list. 2. Then it looses the confirmation keeping the entry unconfirmed. 3. Second clone now wants to commit labels and adds the new extension for that breaking the pointer in the expectation list causing UAF on the destruction path later. While this is possible to trigger, there should be no practical network pipeline where committing both clones without modifications into the same zone is needed. So, let's just reset the entry in case for some reason we got an skb with a shared one during commit. This doesn't affect any known use cases, but avoids any potential problems with sharing and modification of the unconfirmed ct entry. The fixes tag points to the introduction of helpers, since that's the main UAF trigger for the sharing. Fixes: cae3a2627520 ("openvswitch: Allow attaching helpers to ct action") Cc: stable@vger.kernel.org Reported-by: Axel Mierczuk Signed-off-by: Ilya Maximets Reviewed-by: Aaron Conole Link: https://patch.msgid.link/20260921145655.3167436-2-i.maximets@ovn.org Signed-off-by: Jakub Kicinski Stable-dep-of: 00df72e39f30 ("net/sched: act_ct: remove 'add_helper' dead code") Signed-off-by: Sasha Levin --- include/net/netfilter/nf_conntrack.h | 5 +++++ net/openvswitch/conntrack.c | 12 ++++++++++++ 2 files changed, 17 insertions(+) diff --git a/include/net/netfilter/nf_conntrack.h b/include/net/netfilter/nf_conntrack.h index aa0a7c82199ec..7e26611eb3c4a 100644 --- a/include/net/netfilter/nf_conntrack.h +++ b/include/net/netfilter/nf_conntrack.h @@ -184,6 +184,11 @@ static inline void nf_ct_put(struct nf_conn *ct) nf_ct_destroy(&ct->ct_general); } +static inline bool nf_ct_shared(const struct nf_conn *ct) +{ + return refcount_read(&ct->ct_general.use) > 1; +} + /* load module; enable/disable conntrack in this namespace */ int nf_ct_netns_get(struct net *net, u8 nfproto); void nf_ct_netns_put(struct net *net, u8 nfproto); diff --git a/net/openvswitch/conntrack.c b/net/openvswitch/conntrack.c index 89ef350ca91c4..a3d839099fdb3 100644 --- a/net/openvswitch/conntrack.c +++ b/net/openvswitch/conntrack.c @@ -734,6 +734,18 @@ static int __ovs_ct_lookup(struct net *net, struct sw_flow_key *key, enum ip_conntrack_info ctinfo; struct nf_conn *ct; + /* If the ct entry is not confirmed and shared with some other skb, + * e.g., a cloned one, we can't just modify it with the commit as we + * must not modify the extension set. Reset. + */ + if (cached && info->commit) { + ct = nf_ct_get(skb, &ctinfo); + if (ct && !nf_ct_is_confirmed(ct) && nf_ct_shared(ct)) { + nf_reset_ct(skb); + cached = false; + } + } + if (!cached) { struct nf_hook_state state = { .hook = NF_INET_PRE_ROUTING, -- 2.53.0