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 31E244FECC3; Tue, 13 Oct 2026 12:16:26 +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=1791893787; cv=none; b=UmWTgjLLn5xXZJKfQ8AcAfADMZxbv5Qtn2mImSQz7zZVU4NWnbsKrd2m5s+9PMAL37CgvYR0pfgcPoWR5s1W87sTfKFfhofQJbC1XtY5USw+RB+EwrEOl3tPXxWjmg1i4bQ6NNKrfrsmjnkqipKe9mgKNrDbtwe0YyLUchR8jzE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791893787; c=relaxed/simple; bh=5iyw+ItSuXi0nRUTvCrUE/KYpQ+BAniOjSj/mzHvtK4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=RCP/Gg1v9D0TkwG35pokXP/JLXZlu/cvqjpsjJHxV4A5QXqCigOIsC+t9KYCVVNAHNwnNubPdl08C5IvGQzWDymHaCekyZZpJnXJ9M/9WZelTpjfoRsXiRXtFvgQ+Z8spQJRjbfo7gosPh6chRXNUpeNoanU5pGqBsTW3DvaTHg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=i6onWIKn; 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="i6onWIKn" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 872611F000FF; Tue, 13 Oct 2026 12:16:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1791893786; bh=OGLPl0Wgz18KaT8aJ+6ShZojv4klEpiTaio5nA8hcWo=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=i6onWIKnsx3sQfWs829RjshaXfhYU7u5bPjhxULQaUzcJiVQatBafPe+QCqw2RFMK qYtoUmql3NB4/HsMWpQkyRXkXRKtzZYJrYMEzzpGXakmDrHddOwH/td/H7C2BCTQd3 PY/BnvgD3D/N+u9upxsdjjgCVKMKz74r+VzoW50w= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Chengfeng Ye , Emil Tsalapatis , Kumar Kartikeya Dwivedi , Sasha Levin Subject: [PATCH 6.18 340/621] bpf: Fix netns reference imbalance in conntrack kfuncs Date: Tue, 13 Oct 2026 13:35:35 +0200 Message-ID: <20261013112928.922751188@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261013112920.855194808@linuxfoundation.org> References: <20261013112920.855194808@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 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Chengfeng Ye [ Upstream commit fdeba03fea78407a8c52faa99177c9f7f29f90eb ] The opts argument of the BPF conntrack kfuncs can point to a shared map value. __bpf_nf_ct_lookup() and __bpf_nf_ct_alloc_entry() read opts->netns_id separately when acquiring and releasing the network namespace reference. The reference imbalance can occur as follows: CPU 0 CPU 1 read opts->netns_id (-1) skip get_net_ns_by_id() write opts->netns_id (id) read opts->netns_id (id) put_net(net) /* no matching get */ The reverse transition leaks the reference. Repeating the unmatched put can destroy a live namespace and crash later users. The kernel reported: Oops: general protection fault, probably for non-canonical address KASAN: null-ptr-deref in range [0x00000000000000e8-0x00000000000000ef] RIP: 0010:bpf_prog_test_run_xdp+0x52c/0x1700 Call Trace: __sys_bpf+0x1662/0x50c0 __x64_sys_bpf+0x73/0xb0 do_syscall_64+0xf9/0x540 entry_SYSCALL_64_after_hwframe+0x77/0x7f Kernel panic - not syncing: Fatal exception Snapshot every input field of opts with READ_ONCE() before validating or using it. The netns_id snapshot keeps the namespace get/put pair balanced, while the other snapshots keep the remaining options from changing partway through an invocation. The individual reads can still observe an inconsistent combination during a concurrent update, but each selected field value remains stable for that invocation. Fixes: aed8ee7feb44 ("net: netfilter: Deduplicate code in bpf_{xdp,skb}_ct_lookup") Fixes: d7e79c97c00c ("net: netfilter: Add kfuncs to allocate and insert CT") Signed-off-by: Chengfeng Ye Reviewed-by: Emil Tsalapatis Link: https://lore.kernel.org/bpf/20260731160921.3245840-1-nicoyip.dev@gmail.com Signed-off-by: Kumar Kartikeya Dwivedi Signed-off-by: Sasha Levin --- net/netfilter/nf_conntrack_bpf.c | 72 +++++++++++++++++++++----------- 1 file changed, 48 insertions(+), 24 deletions(-) diff --git a/net/netfilter/nf_conntrack_bpf.c b/net/netfilter/nf_conntrack_bpf.c index 16c3729485376..aef1770255121 100644 --- a/net/netfilter/nf_conntrack_bpf.c +++ b/net/netfilter/nf_conntrack_bpf.c @@ -121,42 +121,54 @@ __bpf_nf_ct_alloc_entry(struct net *net, struct bpf_sock_tuple *bpf_tuple, struct nf_conntrack_tuple otuple, rtuple; struct nf_conntrack_zone ct_zone; struct nf_conn *ct; + u8 ct_zone_dir = 0; + u16 ct_zone_id; + s32 netns_id; + u8 l4proto; int err; if (!(opts_len == NF_BPF_CT_OPTS_SZ || opts_len == 12)) return ERR_PTR(-EINVAL); + + netns_id = READ_ONCE(opts->netns_id); + l4proto = READ_ONCE(opts->l4proto); + ct_zone_id = READ_ONCE(opts->ct_zone_id); if (opts_len == NF_BPF_CT_OPTS_SZ) { - if (opts->reserved[0] || opts->reserved[1] || opts->reserved[2]) + ct_zone_dir = READ_ONCE(opts->ct_zone_dir); + if (READ_ONCE(opts->reserved[0]) || + READ_ONCE(opts->reserved[1]) || + READ_ONCE(opts->reserved[2])) return ERR_PTR(-EINVAL); } else { - if (opts->ct_zone_id) + if (ct_zone_id) return ERR_PTR(-EINVAL); } - if (unlikely(opts->netns_id < BPF_F_CURRENT_NETNS)) + if (unlikely(netns_id < BPF_F_CURRENT_NETNS)) return ERR_PTR(-EINVAL); - err = bpf_nf_ct_tuple_parse(bpf_tuple, tuple_len, opts->l4proto, + err = bpf_nf_ct_tuple_parse(bpf_tuple, tuple_len, l4proto, IP_CT_DIR_ORIGINAL, &otuple); if (err < 0) return ERR_PTR(err); - err = bpf_nf_ct_tuple_parse(bpf_tuple, tuple_len, opts->l4proto, + err = bpf_nf_ct_tuple_parse(bpf_tuple, tuple_len, l4proto, IP_CT_DIR_REPLY, &rtuple); if (err < 0) return ERR_PTR(err); - if (opts->netns_id >= 0) { - net = get_net_ns_by_id(net, opts->netns_id); + if (netns_id >= 0) { + net = get_net_ns_by_id(net, netns_id); if (unlikely(!net)) return ERR_PTR(-ENONET); } if (opts_len == NF_BPF_CT_OPTS_SZ) { - if (opts->ct_zone_dir == 0) - opts->ct_zone_dir = NF_CT_DEFAULT_ZONE_DIR; - nf_ct_zone_init(&ct_zone, - opts->ct_zone_id, opts->ct_zone_dir, 0); + if (ct_zone_dir == 0) { + ct_zone_dir = NF_CT_DEFAULT_ZONE_DIR; + opts->ct_zone_dir = ct_zone_dir; + } + nf_ct_zone_init(&ct_zone, ct_zone_id, ct_zone_dir, 0); } else { ct_zone = nf_ct_zone_dflt; } @@ -170,7 +182,7 @@ __bpf_nf_ct_alloc_entry(struct net *net, struct bpf_sock_tuple *bpf_tuple, __nf_ct_set_timeout(ct, timeout * HZ); out: - if (opts->netns_id >= 0) + if (netns_id >= 0) put_net(net); return ct; @@ -185,46 +197,58 @@ static struct nf_conn *__bpf_nf_ct_lookup(struct net *net, struct nf_conntrack_tuple tuple; struct nf_conntrack_zone ct_zone; struct nf_conn *ct; + u8 ct_zone_dir = 0; + u16 ct_zone_id; + s32 netns_id; + u8 l4proto; int err; if (!opts || !bpf_tuple) return ERR_PTR(-EINVAL); if (!(opts_len == NF_BPF_CT_OPTS_SZ || opts_len == 12)) return ERR_PTR(-EINVAL); + + netns_id = READ_ONCE(opts->netns_id); + l4proto = READ_ONCE(opts->l4proto); + ct_zone_id = READ_ONCE(opts->ct_zone_id); if (opts_len == NF_BPF_CT_OPTS_SZ) { - if (opts->reserved[0] || opts->reserved[1] || opts->reserved[2]) + ct_zone_dir = READ_ONCE(opts->ct_zone_dir); + if (READ_ONCE(opts->reserved[0]) || + READ_ONCE(opts->reserved[1]) || + READ_ONCE(opts->reserved[2])) return ERR_PTR(-EINVAL); } else { - if (opts->ct_zone_id) + if (ct_zone_id) return ERR_PTR(-EINVAL); } - if (unlikely(opts->l4proto != IPPROTO_TCP && opts->l4proto != IPPROTO_UDP)) + if (unlikely(l4proto != IPPROTO_TCP && l4proto != IPPROTO_UDP)) return ERR_PTR(-EPROTO); - if (unlikely(opts->netns_id < BPF_F_CURRENT_NETNS)) + if (unlikely(netns_id < BPF_F_CURRENT_NETNS)) return ERR_PTR(-EINVAL); - err = bpf_nf_ct_tuple_parse(bpf_tuple, tuple_len, opts->l4proto, + err = bpf_nf_ct_tuple_parse(bpf_tuple, tuple_len, l4proto, IP_CT_DIR_ORIGINAL, &tuple); if (err < 0) return ERR_PTR(err); - if (opts->netns_id >= 0) { - net = get_net_ns_by_id(net, opts->netns_id); + if (netns_id >= 0) { + net = get_net_ns_by_id(net, netns_id); if (unlikely(!net)) return ERR_PTR(-ENONET); } if (opts_len == NF_BPF_CT_OPTS_SZ) { - if (opts->ct_zone_dir == 0) - opts->ct_zone_dir = NF_CT_DEFAULT_ZONE_DIR; - nf_ct_zone_init(&ct_zone, - opts->ct_zone_id, opts->ct_zone_dir, 0); + if (ct_zone_dir == 0) { + ct_zone_dir = NF_CT_DEFAULT_ZONE_DIR; + opts->ct_zone_dir = ct_zone_dir; + } + nf_ct_zone_init(&ct_zone, ct_zone_id, ct_zone_dir, 0); } else { ct_zone = nf_ct_zone_dflt; } hash = nf_conntrack_find_get(net, &ct_zone, &tuple); - if (opts->netns_id >= 0) + if (netns_id >= 0) put_net(net); if (!hash) return ERR_PTR(-ENOENT); -- 2.53.0