[PATCH 6/6] proc: Set correct userns for new proc super created by a new pid_namespace

[David Howells]

From: Andrei Vagin <ava...@openvz.org>

Fix the setting up a new proc superblock for a new pid_namespace such that
the user_ns for that proc superblock needs to be taken from the new
pid_namespace and not the active process.

Signed-off-by: Andrei Vagin <ava...@gmail.com>
Signed-off-by: David Howells <dhowe...@redhat.com>
---

 fs/proc/root.c |    5 +++++
 1 file changed, 5 insertions(+)

diff --git a/fs/proc/root.c b/fs/proc/root.c
index 1d6e5bfa30cc..1419b48a89ab 100644
--- a/fs/proc/root.c
+++ b/fs/proc/root.c
@@ -315,6 +315,11 @@ int pid_ns_prepare_proc(struct pid_namespace *ns)
        if (IS_ERR(fc))
                return PTR_ERR(fc);
 
+       if (fc->user_ns != ns->user_ns) {
+               put_user_ns(fc->user_ns);
+               fc->user_ns = get_user_ns(ns->user_ns);
+       }
+
        ctx = fc->fs_private;
        if (ctx->pid_ns != ns) {
                put_pid_ns(ctx->pid_ns);