Re: [PATCH 24/30] x86, kaiser: disable native VSYSCALL

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Thu, Nov 9, 2017 at 4:57 PM, Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> wrote:
> On 11/09/2017 04:53 PM, Andy Lutomirski wrote:
>>> The KAISER code attempts to "poison" the user portion of the kernel page
>>> tables.  It detects the entries pages that it wants that it wants to
>>> poison in two ways:
>>>  * Looking for addresses >= PAGE_OFFSET
>>>  * Looking for entries without _PAGE_USER set
>> What do you mean "poison"?
>
> I meant the _PAGE_NX magic that we do in here:
>
> https://git.kernel.org/pub/scm/linux/kernel/git/daveh/x86-kaiser.git/commit/?h=kaiser-414rc7-20171108&id=c4f7d0819170761f092fcf2327b85b082368e73a
>
> to ensure that userspace is unable to run on the kernel PGD.

Aha, I get it.  Why not just drop the _PAGE_USER check?  You could
instead warn if you see a _PAGE_USER page that doesn't have the
correct address for the vsyscall.

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxx.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>



[Index of Archives]     [Linux ARM Kernel]     [Linux ARM]     [Linux Omap]     [Fedora ARM]     [IETF Annouce]     [Bugtraq]     [Linux OMAP]     [Linux MIPS]     [eCos]     [Asterisk Internet PBX]     [Linux API]
  Powered by Linux