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SubjectRe: [S390] mm: add devmem_is_allowed() for STRICT_DEVMEM checking
On Tue, Nov 16, 2010 at 11:59:03PM +0000, Linux Kernel wrote:
> Gitweb: http://git.kernel.org/linus/ec6743bb06510c7b629603ce35713d6ae9273579
> Commit: ec6743bb06510c7b629603ce35713d6ae9273579
> Parent: ca768b663131ca644689fcadc9ca092dcc96a758
> Author: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
> AuthorDate: Wed Nov 10 10:05:55 2010 +0100
> Committer: Martin Schwidefsky <sky@mschwide.boeblingen.de.ibm.com>
> CommitDate: Wed Nov 10 10:05:54 2010 +0100
>
> [S390] mm: add devmem_is_allowed() for STRICT_DEVMEM checking
>
> Provide the devmem_is_allowed() routine to restrict access to
> kernel memory from userspace.
> Set the CONFIG_STRICT_DEVMEM config option to switch on checking.
>
> Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

[snip add kconfig]

...

> +static inline int devmem_is_allowed(unsigned long pfn)
> +{
> + return 0;
> +}

So you add the config option that promises security, but then you always
allow the access. This seems pointless ? Why bother having the option at all?

Dave



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