Re: [PATCH 1/2] pstore: check PSTORE_FLAGS_FRAGILE in pstore_unregister

From: Kees Cook
Date: Fri Oct 23 2015 - 12:54:37 EST


On Fri, Oct 23, 2015 at 7:56 AM, Geliang Tang <geliangtang@xxxxxxx> 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@xxxxxxx>

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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