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Re: [PATCH 03/18] pstore: Avoid race in module unloading

From Namhyung Kim <namhyung@gmail.com>
Newsgroups linux.kernel
Subject Re: [PATCH 03/18] pstore: Avoid race in module unloading
Date 2017-03-07 17:30 +0100
Message-ID <tiq9Q-1Dp-11@gated-at.bofh.it> (permalink)
References <ti98Z-6eI-5@gated-at.bofh.it> <ti9iF-6ij-1@gated-at.bofh.it>
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Hi Kees,

On Tue, Mar 7, 2017 at 6:55 AM, Kees Cook <keescook@chromium.org> wrote:
> Technically, it might be possible for struct pstore_info to go out of
> scope after the module_put(), so report the backend name first.

But in that case, using pstore will crash the kernel anyway, right?
If so, why pstore doesn't keep a reference until unregister?
Do I miss something?

Thanks,
Namhyung


>
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
>  fs/pstore/platform.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
> index 074fe85a2078..d69ef8a840b9 100644
> --- a/fs/pstore/platform.c
> +++ b/fs/pstore/platform.c
> @@ -722,10 +722,10 @@ int pstore_register(struct pstore_info *psi)
>          */
>         backend = psi->name;
>
> -       module_put(owner);
> -
>         pr_info("Registered %s as persistent store backend\n", psi->name);
>
> +       module_put(owner);
> +
>         return 0;
>  }
>  EXPORT_SYMBOL_GPL(pstore_register);
> --
> 2.7.4
>

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Thread

[PATCH 03/18] pstore: Avoid race in module unloading Kees Cook <keescook@chromium.org> - 2017-03-06 23:30 +0100
  Re: [PATCH 03/18] pstore: Avoid race in module unloading Namhyung Kim <namhyung@gmail.com> - 2017-03-07 17:30 +0100
    Re: [PATCH 03/18] pstore: Avoid race in module unloading Kees Cook <keescook@chromium.org> - 2017-03-07 19:30 +0100

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