From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794046565; b=JvCkNCmHmNc6lB6OYIBVKAOXbuellXjlgBMaBArFlHUMavSsq55pexdS1nV5DS5QYwaG 6trTLwPmmBoV6QzYvxWmq8ZL4BsfLVg3ficcl/01YKNSeXVdZcxDuISYUjInFHMW2L0sY 4K+Cu/or/rV5PujQg0BSuoKcApYlsSbs2vv2qQD82GuMRYV4/Nl0P5XJBdMzAaYwf00xs EAF4ATaqW6RrbPuXXkE8BiWzi7p0wLW+tM1y7MPXYTkzL/HlWt74nReKKJvWkT5X/9GA6 nOBpd53fOCl3pVBmcKKiMLBFaa/BfIV75xbL8r1i8blgRG7uNwnltsLiDpY7YuYnq4A== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794046565; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=bHrAuYfO9evY3XqOQE8n6WXXDGMIvXwvCH4MXSZnkYs=; b=thyx1dYaQJPJGxvxdpvW3a135GENpPlx1ro1mhkDsLVXsL1W+Q/qS3bWOBTHAaqhoUW6 ETpBR6+E6rO2sgv1a2C6KdHxkc/R9vIbmgkdnpAKIpCI85DJCo6bzRVGnLxwMnH9SWawC OUL8r6C0y3zEzb2u/v2EPaTZbgTIPIkzQDAkFRKmJ2dRdw6AXUJQ5EwJTCagbleaMP3wz RFDEto1VDWTKm4Vi/3LxT0O6y52yymFTnENHIXlN/5CCaDzmu6wM+TGZGahcwUptWaAEt gNKdGFhvBZv/A/ZFZ5xyxCOtq+8YrtuMgWPdUPjlbYB/rcfRaV0RyM5VPUUyaPW0OIw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=Llfi803d; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9A8E6606A326 for ; Sat, 7 Nov 2026 10:16:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=Llfi803d Received: by smtp.kernel.org (Postfix) with ESMTPSA id 13F3E1F008A1; Sat, 7 Nov 2026 10:16:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794046565; bh=bHrAuYfO9evY3XqOQE8n6WXXDGMIvXwvCH4MXSZnkYs=; h=From:To:Cc:Subject:Date; b=Llfi803dfrZHqRrDc+DrwhXSsT4ngCj00i5Fk1Zl9qCLdLHK/i5eDLcEWdGzvOhb3 7xa1J/rPbJGr0OaKS90QhIfDEu70M3UkNqd8JLcdg5//fhov53CbjhXBvEQIWBAcNu xgwvIFmguRlD4odXZcPzAM7GnJMHALVBUYrUiQq/vRtz1wkU96oEgq9aPARP9wqprd V5WMH3/CzybbFJixvEIvnI6qumP+RLOFhYpjYFqbpFaDZisdktheCS5c4Cu5pqucp0 4KiDijJ1BhdtD9YUftmhGsNAzH+urfiiBSIqaqlW9f5AyXrMUXIpmALfMAtHwdXIY2 bRzlsa37gatCg== From: Sasha Levin To: brauner@kernel.org, yi1.lai@intel.com Cc: stable@vger.kernel.org Subject: FAILED: patch "[PATCH] ns: don't add init_ipc_ns and init_net without namespace support" failed to apply to 6.18-stable tree Date: Sat, 7 Nov 2026 05:16:03 -0500 Message-ID: <20261107051603-failed-6.18-82f1c815aaef@kernel.org> X-Mailer: git-send-email 2.53.0 X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.18-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.18.y git checkout FETCH_HEAD git cherry-pick -x 82f1c815aaef1905c5c6c386c8a0d74f6ff70a54 # git commit -s git send-email --to '' --in-reply-to '20261107051603-failed-6.18-82f1c815aaef@kernel.org' --subject-prefix 'PATCH 6.18.y' 'HEAD^..' Thanks, Sasha ------------------ original commit in Linus's tree ------------------ >From 82f1c815aaef1905c5c6c386c8a0d74f6ff70a54 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Fri, 30 Oct 2026 16:50:07 +0100 Subject: [PATCH] ns: don't add init_ipc_ns and init_net without namespace support When CONFIG_IPC_NS or CONFIG_NET_NS are turned off we still add the initial ipc and network namespace to the namespace trees. ipc_ns_init() calls ns_tree_add(&init_ipc_ns) whenever CONFIG_SYSVIPC is set and setup_net() calls ns_tree_add_raw() on init_net whenever CONFIG_NET is set. But without CONFIG_IPC_NS and CONFIG_NET_NS these aren't namespaces userspace can do anything with. They don't have proc_ns_operations so there's no /proc//ns/{ipc,net} for them, nsfs_fh_to_dentry() refuses them with -EOPNOTSUPP, and since ns->ops is NULL __ns_tree_add_raw() doesn't add them to the owner list of init_user_ns either. So they end up half registered. That's also not how we treat any of the other namespace types. Without CONFIG_UTS_NS, CONFIG_PID_NS, CONFIG_TIME_NS or CONFIG_USER_NS the initial namespace is never added to the tree. listns() walks the unified tree and calls is_current_namespace() for every namespace it finds via may_list_ns(). But is_current_namespace() only knows about CLONE_NEWIPC and CLONE_NEWNET if CONFIG_IPC_NS and CONFIG_NET_NS are set. Otherwise we end up in the default case and its VFS_WARN_ON_ONCE(). Any unprivileged caller can trigger that with a plain listns() call: WARNING: CPU: 0 PID: 526 at fs/nsfs.c:508 is_current_namespace+0x12f/0x440 Call Trace: legitimize_ns+0x25f/0x4c0 do_listns+0x185/0x5c0 __do_sys_listns+0x13b/0x300 Instead of teaching is_current_namespace() about namespaces that can't be opened, only add the initial namespaces to the tree if their namespace type is enabled. Move the registration of init_ipc_ns into ipc/namespace.c which is only built with CONFIG_IPC_NS. That also fixes CONFIG_SYSVIPC=n, CONFIG_POSIX_MQUEUE=y, CONFIG_IPC_NS=y where ipc/shm.c isn't built and init_ipc_ns was never added at all. For the network namespace only call ns_tree_add_raw() if CONFIG_NET_NS is set. Without CONFIG_NET_NS cleanup_net() isn't built and init_net is never removed so there's nothing to balance. Fixes: 74b24a582e1f ("ipc: support ns lookup") Fixes: 195f7422298d ("net: support ns lookup") Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-lkp/202610260917.6248e316-lkp@intel.com Cc: stable@vger.kernel.org # v6.18+ Link: https://patch.msgid.link/20261030-work-nsfs-init_ns_tree-v1-1-7ec0adb47c54@kernel.org Signed-off-by: Christian Brauner (Amutable) --- ipc/namespace.c | 7 +++++++ ipc/shm.c | 2 -- net/core/net_namespace.c | 4 +++- 3 files changed, 10 insertions(+), 3 deletions(-) diff --git a/ipc/namespace.c b/ipc/namespace.c index 75aa7b4693484..b54d23fd83d70 100644 --- a/ipc/namespace.c +++ b/ipc/namespace.c @@ -255,3 +255,10 @@ const struct proc_ns_operations ipcns_operations = { .install = ipcns_install, .owner = ipcns_owner, }; + +static int __init ipc_ns_tree_init(void) +{ + ns_tree_add(&init_ipc_ns); + return 0; +} +pure_initcall(ipc_ns_tree_init); diff --git a/ipc/shm.c b/ipc/shm.c index bb1a721a3e746..cbab3d16cf70b 100644 --- a/ipc/shm.c +++ b/ipc/shm.c @@ -45,7 +45,6 @@ #include #include #include -#include #include @@ -149,7 +148,6 @@ void shm_exit_ns(struct ipc_namespace *ns) static int __init ipc_ns_init(void) { shm_init_ns(&init_ipc_ns); - ns_tree_add(&init_ipc_ns); return 0; } diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c index da5f881fbd3b9..52c2bd44778a8 100644 --- a/net/core/net_namespace.c +++ b/net/core/net_namespace.c @@ -447,7 +447,9 @@ static __net_init int setup_net(struct net *net) down_write(&net_rwsem); list_add_tail_rcu(&net->list, &net_namespace_list); up_write(&net_rwsem); - ns_tree_add_raw(net); + /* Without CONFIG_NET_NS init_net isn't exposed as a namespace. */ + if (IS_ENABLED(CONFIG_NET_NS)) + ns_tree_add_raw(net); out: return error; -- 2.53.0