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>
---
fs/proc/base.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 96ee899d6502..989e3078d7af 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -350,6 +350,8 @@ static int lstats_open(struct inode *inode, struct file *file)
struct seq_file *m;
struct task_struct *task = get_proc_task(inode);
+ if (!task)
+ return -ENOENT;
ret = single_open(file, lstats_show_proc, NULL);
if (!ret) {
m = file->private_data;