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From: Boris Ostrovsky <boris.ostrovsky@oracle.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>,
	Andy Lutomirski <luto@kernel.org>, X86 ML <x86@kernel.org>,
	Borislav Petkov <bp@alien8.de>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Cc: "security@kernel.org" <security@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	xen-devel <xen-devel@lists.xen.org>,
	Jan Beulich <jbeulich@suse.com>,
	Sasha Levin <sasha.levin@oracle.com>
Subject: Re: [PATCH v6 0/4] x86: modify_ldt improvement, test, and config option
Date: Fri, 31 Jul 2015 09:44:24 -0400	[thread overview]
Message-ID: <55BB7BB8.5060903__16334.0564504781$1438350422$gmane$org@oracle.com> (raw)
In-Reply-To: <55BB3B72.6060607@citrix.com>

On 07/31/2015 05:10 AM, Andrew Cooper wrote:
> On 30/07/15 22:31, Andy Lutomirski wrote:
>> This is intended for x86/urgent.  Sorry for taking so long, but it
>> seemed nice to avoid breaking Xen.
> Very much appreciated.  Thanks!
>
>> This fixes the "dazed and confused" issue which was exposed by the
>> CVE-2015-5157 fix.  It's also probably a good general attack surface
>> reduction, and it replaces some scary code with IMO less scary code.
>>
>> Also, servers and embedded systems should probably turn off modify_ldt.
>> This makes that possible.
>>
>> Xen people, can you test patch 1?  It works for me on my evil 32-bit
>> Xen virtio setup.
> So the LDT issue seems to have gone away, which is good.
>
> However, I did get this from my single vcpu guest test
>
> [OK]    LDT entry 0 is invalid
> [SKIP]    Cannot set affinity to CPU 1
> [RUN]    Test exec
> [    3.638967] CPU 0 set the LDT
> [OK]    LDT entry 0 has AR 0x0040FA00 and limit 0x0000002A
> [    3.639380] ------------[ cut here ]------------
> [    3.639389] WARNING: CPU: 0 PID: 383 at
> /local/linux-mainline.git/arch/x86/include/asm/mmu_context.h:96
> flush_old_exec+0x7fd/0xb70()
> [    3.639397] DEBUG_LOCKS_WARN_ON(!irqs_disabled())

You must be running v5 (or earlier). This is fixed in v6 --- it is now 
'DEBUG_LOCKS_WARN_ON(preemptible());'


-boris

  reply	other threads:[~2015-07-31 13:44 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-07-30 21:31 [PATCH v6 0/4] x86: modify_ldt improvement, test, and config option Andy Lutomirski
2015-07-30 21:31 ` [PATCH v6 1/4] x86/xen: Probe target addresses in set_aliased_prot before the hypercall Andy Lutomirski
2015-07-30 21:31 ` Andy Lutomirski
2015-07-31  9:41   ` [Xen-devel] " David Vrabel
2015-07-31  9:41   ` David Vrabel
2015-07-31 13:56   ` [tip:x86/asm] x86/xen: Probe target addresses in set_aliased_prot () " tip-bot for Andy Lutomirski
2015-07-31 13:56   ` tip-bot for Andy Lutomirski
2015-07-30 21:31 ` [PATCH v6 2/4] x86/ldt: Make modify_ldt synchronous Andy Lutomirski
2015-07-30 22:50   ` Andrew Cooper
2015-07-31  3:15     ` Andy Lutomirski
2015-07-31  3:15     ` Andy Lutomirski
2015-07-30 22:50   ` Andrew Cooper
2015-07-31 13:56   ` [tip:x86/asm] " tip-bot for Andy Lutomirski
2015-07-31 13:56   ` tip-bot for Andy Lutomirski
2015-07-30 21:31 ` [PATCH v6 2/4] " Andy Lutomirski
2015-07-30 21:31 ` [PATCH v6 3/4] selftests/x86, x86/ldt: Add a selftest for modify_ldt Andy Lutomirski
2015-07-31 13:57   ` [tip:x86/asm] selftests/x86, x86/ldt: Add a selftest for modify_ldt() tip-bot for Andy Lutomirski
2015-07-31 13:57   ` tip-bot for Andy Lutomirski
2015-07-30 21:31 ` [PATCH v6 3/4] selftests/x86, x86/ldt: Add a selftest for modify_ldt Andy Lutomirski
2015-07-30 21:31 ` [PATCH v6 4/4] x86/ldt: Make modify_ldt optional Andy Lutomirski
2015-07-30 21:31 ` Andy Lutomirski
2015-07-31 13:49   ` Ingo Molnar
2015-07-31 13:49   ` Ingo Molnar
2015-07-31 14:02   ` [tip:x86/asm] x86/ldt: Make modify_ldt() optional tip-bot for Andy Lutomirski
2015-07-31 14:02   ` tip-bot for Andy Lutomirski
2015-07-31  9:10 ` [PATCH v6 0/4] x86: modify_ldt improvement, test, and config option Andrew Cooper
2015-07-31 13:44   ` Boris Ostrovsky [this message]
2015-07-31 13:44   ` Boris Ostrovsky
2015-07-31 14:02     ` Andrew Cooper
2015-07-31 14:02       ` Andrew Cooper
2015-07-31  9:10 ` Andrew Cooper
  -- strict thread matches above, loose matches on Subject: below --
2015-07-30 21:31 Andy Lutomirski

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