Re: [PATCH] hpet, allow user controlled mmap for user processes

From: Clemens Ladisch
Date: Sat Mar 16 2013 - 05:56:21 EST

Prarit Bhargava wrote:
> The CONFIG_HPET_MMAP Kconfig option exposes the memory map of the HPET
> registers to userspace. The Kconfig help points out that in some cases this
> can be a security risk as some systems may erroneously configure the map such
> that additional data is exposed to userspace.

I'm not aware of any such system (but cannot rule out the possibility).

> In an effort to mitigate this risk, and due to the low number of users
> of the MMAP functionality I've introduced a kernel parameter,
> hpet_mmap_enable, that is required in order to actually have the HPET
> MMAP exposed.

This introduces a regression for all users. At least make the default
state (allowed/forbidden) configurable.

Also, this patch makes the Kconfig help text a lie.

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