[PATCH 5.5 110/151] pid: Fix error return value in some cases

[Greg Kroah-Hartman]

From: Corey Minyard <cminyard@xxxxxxxxxx>

commit b26ebfe12f34f372cf041c6f801fa49c3fb382c5 upstream.

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@xxxxxxxxxx>
Acked-by: Christian Brauner <christian.brauner@xxxxxxxxxx>
Cc: Andrei Vagin <avagin@xxxxxxxxx>
Cc: Dmitry Safonov <0x7f454c46@xxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Adrian Reber <areber@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # 5.5
Link: https://lore.kernel.org/r/20200306172314.12232-1-minyard@xxxxxxx
[christian.brauner@xxxxxxxxxx: fixup commit message]
Signed-off-by: Christian Brauner <christian.brauner@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 kernel/pid.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -247,6 +247,8 @@ struct pid *alloc_pid(struct pid_namespa
 		tmp = tmp->parent;
 	}
 
+	retval = -ENOMEM;
+
 	if (unlikely(is_child_reaper(pid))) {
 		if (pid_ns_prepare_proc(ns))
 			goto out_free;