cgroup: add cgroup namespace to tree after owner is set

[ Upstream commit 768b1565d9d1e1eebf7567f477f7f46c05a98a4d ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/kernel/cgroup/namespace.c b/kernel/cgroup/namespace.c
index fdbe57578e688624ce194ddefe7d9efb30822dd9..db9617556dd70671ef68a6ce282600911ee7deb8 100644 (file)
--- 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;
 }