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Re: [Xen-devel] [PATCH v4 0/3] x86: modify_ldt improvement, test, and config option
- To: Andy Lutomirski <luto@xxxxxxxxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
- From: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
- Date: Tue, 28 Jul 2015 13:10:41 -0400
- Cc: "security@xxxxxxxxxx" <security@xxxxxxxxxx>, Peter Zijlstra <peterz@xxxxxxxxxxxxx>, X86 ML <x86@xxxxxxxxxx>, "linux-kernel@xxxxxxxxxxxxxxx" <linux-kernel@xxxxxxxxxxxxxxx>, Steven Rostedt <rostedt@xxxxxxxxxxx>, xen-devel <xen-devel@xxxxxxxxxxxxx>, Borislav Petkov <bp@xxxxxxxxx>, Jan Beulich <jbeulich@xxxxxxxx>, Sasha Levin <sasha.levin@xxxxxxxxxx>
- Delivery-date: Tue, 28 Jul 2015 17:12:03 +0000
- List-id: Xen developer discussion <xen-devel.lists.xen.org>
On 07/28/2015 01:07 PM, Andy Lutomirski wrote:
On Tue, Jul 28, 2015 at 9:30 AM, Andrew Cooper
<andrew.cooper3@xxxxxxxxxx> wrote:
I suspect that the set_ldt(NULL, 0) call hasn't reached Xen before
xen_free_ldt() is attempting to nab back the pages which Xen still has
mapped as an LDT.
I just instrumented it with yet more LSL instructions. I'm pretty
sure that set_ldt really is clearing at least LDT entry zero.
Nonetheless the free_ldt call still oopses.
Yes, I added some instrumentation to the hypervisor and we definitely
set LDT to NULL before failing.
-boris
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- References:
- [Xen-devel] [PATCH v4 0/3] x86: modify_ldt improvement, test, and config option
- Re: [Xen-devel] [PATCH v4 0/3] x86: modify_ldt improvement, test, and config option
- Re: [Xen-devel] [PATCH v4 0/3] x86: modify_ldt improvement, test, and config option
- Re: [Xen-devel] [PATCH v4 0/3] x86: modify_ldt improvement, test, and config option
- Re: [Xen-devel] [PATCH v4 0/3] x86: modify_ldt improvement, test, and config option
- Re: [Xen-devel] [PATCH v4 0/3] x86: modify_ldt improvement, test, and config option
- Re: [Xen-devel] [PATCH v4 0/3] x86: modify_ldt improvement, test, and config option
- Re: [Xen-devel] [PATCH v4 0/3] x86: modify_ldt improvement, test, and config option
- Re: [Xen-devel] [PATCH v4 0/3] x86: modify_ldt improvement, test, and config option
- Re: [Xen-devel] [PATCH v4 0/3] x86: modify_ldt improvement, test, and config option
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