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Re: [Xen-devel] [PATCH] x86/hvm: Fix use-after-free introduced by c/s 428607a
- To: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Jan Beulich <JBeulich@xxxxxxxx>
- From: Corneliu ZUZU <czuzu@xxxxxxxxxxxxxxx>
- Date: Tue, 2 Feb 2016 14:51:11 +0200
- Cc: Xen-devel <xen-devel@xxxxxxxxxxxxx>
- Comment: DomainKeys? See http://domainkeys.sourceforge.net/
- Delivery-date: Tue, 02 Feb 2016 12:51:25 +0000
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On 2/2/2016 2:05 PM, Andrew Cooper wrote:
Xen and PV guests share the virtual address space, in exactly the same
way as a native kernel and its userspace. PV guests can map pages at
0. Therefore, if Xen were to accidentally follow a NULL pointer, it
may not result in a pagefault. (Hardware mechanisms such as SMEP and
SMAP are added protection against this, but don't work on older hardware)
~Andrew
Thank you, I finally got it.
(I also read
http://wiki.xenproject.org/wiki/X86_Paravirtualised_Memory_Management ,
cleared things up)
Corneliu.
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