linux-kernel - Re: [PATCH v3 0/3] pstore: add pstore unregister

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Date:	Tue, 20 Oct 2015 10:19:09 -0700
From:	Kees Cook <keescook@...omium.org>
To:	Geliang Tang <geliangtang@....com>
Cc:	Anton Vorontsov <anton@...msg.org>,
	Colin Cross <ccross@...roid.com>,
	Tony Luck <tony.luck@...el.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 0/3] pstore: add pstore unregister

On Tue, Oct 20, 2015 at 12:39 AM, Geliang Tang <geliangtang@....com> wrote:
> On Mon, Oct 19, 2015 at 10:56:54PM +0000, Luck, Tony wrote:
>> Thanks for looking to close out this TODO item.
>>
>> The thing that scared me about unloading pstore was what happens to
>> a process that is in the middle of reading some /sys/fs/pstore/file-name-here

Were you able to verify that this reading-while-rmmod case works correctly?

-Kees

>>
>> Do we have all the right reference counts to make sure that process doesn't do
>> weird things if you rmmod pstore in the middle of a read? Or for a subsequent
>> read from the still-open file descriptor?
>>
>> -Tony
>
> Thanks for your review. I updated the patches as you suggested.
>
> // Increase a reference count when pstore file is read.
>  static const struct file_operations pstore_file_operations = {
> +       .owner          = THIS_MODULE,
>         .open           = pstore_file_open,
>         .read           = pstore_file_read,
>         .llseek         = pstore_file_llseek,
>
> // Increase a reference count when pstore is mounted.
>  static struct file_system_type pstore_fs_type = {
> +       .owner          = THIS_MODULE,
>         .name           = "pstore",
>         .mount          = pstore_mount,
>         .kill_sb        = pstore_kill_sb,
>
> ---
> Changes in v3:
>  - Increase a reference count when pstore is used.
> Changes in v2:
>  - Add pstore filesystem unregister.
>  - update commit log.
> ---
>
> Geliang Tang (3):
>   pstore: add vmalloc error check
>   pstore: add a helper function pstore_register_kmsg
>   pstore: add pstore unregister
>
>  fs/pstore/Kconfig      |  2 +-
>  fs/pstore/Makefile     |  6 +++---
>  fs/pstore/ftrace.c     | 23 ++++++++++++++++++-----
>  fs/pstore/inode.c      |  9 +++++++++
>  fs/pstore/internal.h   |  4 ++++
>  fs/pstore/platform.c   | 42 +++++++++++++++++++++++++++++++++++++++++-
>  fs/pstore/pmsg.c       |  9 +++++++++
>  fs/pstore/ram.c        | 17 +++++++----------
>  include/linux/pstore.h | 14 +-------------
>  kernel/printk/printk.c |  1 +
>  10 files changed, 94 insertions(+), 33 deletions(-)
>
> --
> 1.9.1
>
>



-- 
Kees Cook
Chrome OS Security
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