From bb2b0051d7b0772ea9d0b4be900c2d965093f5d7 Mon Sep 17 00:00:00 2001
From: Ming Lei <ming.lei@canonical.com>
Date: Thu, 4 Apr 2013 22:22:37 +0800
Subject: [PATCH] sysfs: check if one entry has been removed before freeing

It might be a kernel disaster if one sysfs entry is freed but
still referenced by sysfs tree.

Recently Dave and Sasha reported one use-after-free problem on
sysfs entry, and the problem has been troubleshooted with help
of debug message added in this patch.

Given sysfs_get_dirent/sysfs_put are exported APIs, even inside
sysfs they are called in many contexts(kobject/attribe add/delete,
inode init/drop, dentry lookup/release, readdir, ...), it is healthful
to check the removed flag before freeing one entry and dump message
if it is freeing without being removed first.

Cc: Dave Jones <davej@redhat.com>
Cc: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
Reading git-format-patch failed