From ae0027869db7d28563cd783865fab04ffd18419c Mon Sep 17 00:00:00 2001
From: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Date: Thu, 14 Feb 2008 10:26:24 -0800
Subject: [PATCH] latencytop: fix kernel panic while reading latency proc file

Reading /proc/<pid>/latency or /proc/<pid>/task/<tid>/latency could cause
NULL pointer dereference.

In lstats_open(), get_proc_task() can return NULL, in which case the kernel
will oops at lstats_show_proc() because m->private is NULL.

When get_proc_task() returns NULL, the kernel should return -ENOENT.

This can be reproduced by the following script.
while :
do
        date
        bash -c 'ls > ls.$$' &
        pid=$!
        cat /proc/$pid/latency &
        cat /proc/$pid/latency &
        cat /proc/$pid/latency &
        cat /proc/$pid/latency
done

Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
Reading git-format-patch failed