linux-kernel - Re: [PATCH] dell-wmi: Stop storing pointers to DMI tables

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Message-ID: <20160114102920.GB5473@eudyptula.hq.kempniu.pl>
Date:	Thu, 14 Jan 2016 11:29:20 +0100
From:	Michał Kępień <kernel@...pniu.pl>
To:	Andy Lutomirski <luto@...nel.org>
Cc:	Pali Rohár <pali.rohar@...il.com>,
	platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Subject: Re: [PATCH] dell-wmi: Stop storing pointers to DMI tables

> The dmi_walk function maps the DMI table, walks it, and unmaps it.
> This means that the dell_bios_hotkey_table that find_hk_type stores
> points to unmapped memory by the time it gets read.
> 
> I've been able to trigger crashes caused by the stale pointer a
> couple of times, but never on a stock kernel.
> 
> Fix it by generating the keymap in the dmi_walk callback instead of
> storing a pointer.
> 
> Cc: stable@...r.kernel.org
> Signed-off-by: Andy Lutomirski <luto@...nel.org>
> ---
> 
> This seems to work on my laptop.  It applies to platform-drivers-x86/for-next.
> 
> drivers/platform/x86/dell-wmi.c | 69 +++++++++++++++++++++++++----------------
>  1 file changed, 42 insertions(+), 27 deletions(-)
> 
> diff --git a/drivers/platform/x86/dell-wmi.c b/drivers/platform/x86/dell-wmi.c
> index 57402c4c394e..52db2721d7e3 100644
> --- a/drivers/platform/x86/dell-wmi.c
> +++ b/drivers/platform/x86/dell-wmi.c
> @@ -116,7 +116,10 @@ struct dell_bios_hotkey_table {
>  
>  };
>  
> -static const struct dell_bios_hotkey_table *dell_bios_hotkey_table;
> +struct dell_dmi_results {
> +	int err;
> +	struct key_entry *keymap;

Nit: keymap can be a const struct key_entry *.

-- 
Best regards,
Michał Kępień