From 73296bc611cee009f3be6b451e827d1425b9c10f Mon Sep 17 00:00:00 2001
From: Frederic Weisbecker <fweisbec@gmail.com>
Date: Tue, 30 Mar 2010 02:33:36 +0200
Subject: [PATCH] procfs: Use generic_file_llseek in /proc/vmcore

/proc/vmcore has no llseek and then falls down to use default_llseek.
This is racy against read_vmcore() that directly manipulates fpos
but it doesn't hold the bkl there so using it in llseek doesn't
protect anything.

Let's use generic_file_llseek() instead.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: John Kacur <jkacur@redhat.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
---
 fs/proc/vmcore.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
index 0872afa58d39..00ef6046d8d2 100644
--- a/fs/proc/vmcore.c
+++ b/fs/proc/vmcore.c
@@ -162,6 +162,7 @@ static ssize_t read_vmcore(struct file *file, char __user *buffer,
 
 static const struct file_operations proc_vmcore_operations = {
 	.read		= read_vmcore,
+	.llseek		= generic_file_llseek,
 };
 
 static struct vmcore* __init get_new_element(void)
-- 
2.20.1