fix create_new_namespaces() return value

dup_mnt_ns() and clone_uts_ns() return NULL on failure.  This is wrong,
create_new_namespaces() uses ERR_PTR() to catch an error.  This means that the
subsequent create_new_namespaces() will hit BUG_ON() in copy_mnt_ns() or
copy_utsname().

Modify create_new_namespaces() to also use the errors returned by the
copy_*_ns routines and not to systematically return ENOMEM.

[oleg@tv-sign.ru: better changelog]
Signed-off-by: Cedric Le Goater <clg@fr.ibm.com>
Cc: Serge E. Hallyn <serue@us.ibm.com>
Cc: Badari Pulavarty <pbadari@us.ibm.com>
Cc: Pavel Emelianov <xemul@openvz.org>
Cc: Herbert Poetzl <herbert@13thfloor.at>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
index 5aa28e2..15a6015 100644
--- a/kernel/nsproxy.c
+++ b/kernel/nsproxy.c
@@ -58,30 +58,41 @@
 			struct fs_struct *new_fs)
 {
 	struct nsproxy *new_nsp;
+	int err;
 
 	new_nsp = clone_nsproxy(tsk->nsproxy);
 	if (!new_nsp)
 		return ERR_PTR(-ENOMEM);
 
 	new_nsp->mnt_ns = copy_mnt_ns(flags, tsk->nsproxy->mnt_ns, new_fs);
-	if (IS_ERR(new_nsp->mnt_ns))
+	if (IS_ERR(new_nsp->mnt_ns)) {
+		err = PTR_ERR(new_nsp->mnt_ns);
 		goto out_ns;
+	}
 
 	new_nsp->uts_ns = copy_utsname(flags, tsk->nsproxy->uts_ns);
-	if (IS_ERR(new_nsp->uts_ns))
+	if (IS_ERR(new_nsp->uts_ns)) {
+		err = PTR_ERR(new_nsp->uts_ns);
 		goto out_uts;
+	}
 
 	new_nsp->ipc_ns = copy_ipcs(flags, tsk->nsproxy->ipc_ns);
-	if (IS_ERR(new_nsp->ipc_ns))
+	if (IS_ERR(new_nsp->ipc_ns)) {
+		err = PTR_ERR(new_nsp->ipc_ns);
 		goto out_ipc;
+	}
 
 	new_nsp->pid_ns = copy_pid_ns(flags, tsk->nsproxy->pid_ns);
-	if (IS_ERR(new_nsp->pid_ns))
+	if (IS_ERR(new_nsp->pid_ns)) {
+		err = PTR_ERR(new_nsp->pid_ns);
 		goto out_pid;
+	}
 
 	new_nsp->user_ns = copy_user_ns(flags, tsk->nsproxy->user_ns);
-	if (IS_ERR(new_nsp->user_ns))
+	if (IS_ERR(new_nsp->user_ns)) {
+		err = PTR_ERR(new_nsp->user_ns);
 		goto out_user;
+	}
 
 	return new_nsp;
 
@@ -99,7 +110,7 @@
 		put_mnt_ns(new_nsp->mnt_ns);
 out_ns:
 	kfree(new_nsp);
-	return ERR_PTR(-ENOMEM);
+	return ERR_PTR(err);
 }
 
 /*