From: Christian Brauner <brauner@kernel.org>
Date: Wed, 29 Oct 2025 12:20:19 +0000 (+0100)
Subject: cgroup: add cgroup namespace to tree after owner is set
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=768b1565d9d1e1eebf7567f477f7f46c05a98a4d;p=thirdparty%2Flinux.git

cgroup: add cgroup namespace to tree after owner is set

Otherwise we trip VFS_WARN_ON_ONC() in __ns_tree_add_raw().

Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-6-2e6f823ebdc0@kernel.org
Fixes: 7c6059398533 ("cgroup: support ns lookup")
Tested-by: syzbot@syzkaller.appspotmail.com
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
---

diff --git a/kernel/cgroup/namespace.c b/kernel/cgroup/namespace.c
index fdbe57578e688..db9617556dd70 100644
--- a/kernel/cgroup/namespace.c
+++ b/kernel/cgroup/namespace.c
@@ -30,7 +30,6 @@ static struct cgroup_namespace *alloc_cgroup_ns(void)
 	ret = ns_common_init(new_ns);
 	if (ret)
 		return ERR_PTR(ret);
-	ns_tree_add(new_ns);
 	return no_free_ptr(new_ns);
 }
 
@@ -86,6 +85,7 @@ struct cgroup_namespace *copy_cgroup_ns(u64 flags,
 	new_ns->ucounts = ucounts;
 	new_ns->root_cset = cset;
 
+	ns_tree_add(new_ns);
 	return new_ns;
 }