pid: Fix error return value in some cases

Recent changes to alloc_pid() allow the pid number to be specified on
the command line.  If set_tid_size is set, then the code scanning the
levels will hard-set retval to -EPERM, overriding it's previous -ENOMEM
value.

After the code scanning the levels, there are error returns that do not
set retval, assuming it is still set to -ENOMEM.

So set retval back to -ENOMEM after scanning the levels.

Fixes: 49cb2fc42ce4 ("fork: extend clone3() to support setting a PID")
Signed-off-by: Corey Minyard <cminyard@mvista.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Andrei Vagin <avagin@gmail.com>
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Adrian Reber <areber@redhat.com>
Cc: <stable@vger.kernel.org> # 5.5
Link: https://lore.kernel.org/r/20200306172314.12232-1-minyard@acm.org
[christian.brauner@ubuntu.com: fixup commit message]
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

diff --git a/kernel/pid.c b/kernel/pid.c
index 0f4ecb5..19645b2 100644 (file)
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -247,6 +247,8 @@ struct pid *alloc_pid(struct pid_namespace *ns, pid_t *set_tid,
                tmp = tmp->parent;
        }
 
+       retval = -ENOMEM;
+
        if (unlikely(is_child_reaper(pid))) {
                if (pid_ns_prepare_proc(ns))
                        goto out_free;