linux-kernel - Re: [PATCH 1/2] pstore: check PSTORE_FLAGS_FRAGILE in pstore

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Date:	Fri, 23 Oct 2015 09:54:31 -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 1/2] pstore: check PSTORE_FLAGS_FRAGILE in pstore_unregister

On Fri, Oct 23, 2015 at 7:56 AM, Geliang Tang <geliangtang@....com> wrote:
> When PSTORE_FLAGS_FRAGILE flag is set, only kmsg is registered in
> pstore_register. So, under these circumstances, only kmsg needs to
> be unregistered in pstore_unregister.
>
> Signed-off-by: Geliang Tang <geliangtang@....com>

Would it make more sense to have the pstore_unregister_* calls be
defensive, like kfree() is? In other words, it would be safe to call
them, even if they hadn't been registered?

Either way, I'm fine with this. Good catch!

-Kees

> ---
>  fs/pstore/platform.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
> index 0aab920..7ad2038 100644
> --- a/fs/pstore/platform.c
> +++ b/fs/pstore/platform.c
> @@ -496,9 +496,12 @@ EXPORT_SYMBOL_GPL(pstore_register);
>
>  void pstore_unregister(struct pstore_info *psi)
>  {
> -       pstore_unregister_pmsg();
> -       pstore_unregister_ftrace();
> -       pstore_unregister_console();
> +       if ((psi->flags & PSTORE_FLAGS_FRAGILE) == 0) {
> +               pstore_unregister_pmsg();
> +               pstore_unregister_ftrace();
> +               pstore_unregister_console();
> +       }
> +
>         pstore_unregister_kmsg();
>
>         free_buf_for_compression();
> --
> 2.5.0
>
>



-- 
Kees Cook
Chrome OS Security
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