Re: x86: fix macro with bad_bios_dmi_table

From: Yinghai Lu
Date: Tue Sep 23 2008 - 04:31:28 EST


On Tue, Sep 23, 2008 at 1:16 AM, Ingo Molnar <mingo@xxxxxxx> wrote:
>
> * Yinghai Lu <yhlu.kernel@xxxxxxxxx> wrote:
>
>> need one blank tail.
>>
>> fix the crash on ingo's test box.
>
> applied to tip/x86/memory-corruption-check, thanks Yinghai!
>
>> --- a/arch/x86/kernel/setup.c
>> +++ b/arch/x86/kernel/setup.c
>> @@ -760,8 +760,8 @@ static struct dmi_system_id __initdata bad_bios_dmi_table[] = {
>> DMI_MATCH(DMI_BIOS_VENDOR, "Phoenix Technologies, LTD"),
>> },
>> },
>> - {}
>> #endif
>> + {}
>> };
>
> i've seen such DMI crashes numerous times, caused by a missing NULL at
> the end of the table. Is there no sane way to detect or robustly avoid
> such run-off-the-end bugs?
>
> how about changing dmi_check_system(table) to a macro, which does
> something like:
>
> __dmi_check_system(&(table), sizeof(table))

ARRAY_SIZE()

>
> and rename dmi_check_system() in drivers/firmware/dmi_scan.c to
> __dmi_check_system() and add the size parameter? That way we could
> remove the need for NULL termination and it's even a size optimization:
> it shrinks those tables a tiny bit.

# git grep dmi_system_id | grep "\[" | wc -l
62

YH
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