Re: Problem with (?) hardened-sources-3.15.x on kvm-vm

On 08/29/14 03:32, Marcin Mirosław wrote:
> W dniu 29.08.2014 o 01:13, Alex Xu pisze:
>> On 28/08/14 05:02 PM, Sven Vermeulen wrote:
>>> On Wed, Aug 27, 2014 at 05:34:20PM +0100, André Aparício wrote:
>>>> I encountered the same problem with qemu/kvm but can't even login, I
>>>> get random segfaults and even failed malloc assertions
>>>> in /sbin/init, /sbin/rc or /bin/login (never past this).
>>>>
>>>> But it works fine with CONFIG_PAX_MEMORY_UDEREF disabled.
>>>
>>> I am not able to reproduce this :-(
>>>
>>> Host and guest are both on 3.15.5-hardened-r2 and both have UDEREF enabled.
>>>
>>> I tried emerging boost on the guest as recommended in another post but this
>>> didn't fail.
>>>
>>> Wkr,
>>>    Sven Vermeulen
>>>
>>
>> My VM has 12 CPUs but I use MAKEOPTS=-j3. Maybe this affects
>> reproducibility.
>>
>> My host is of unknown kernel, but I'm pretty sure it's not Gentoo, let
>> alone Hardened.
>>
>> Also, I am using <cpu mode="host-passthrough"/> in libvirt (equivalent
>> to -cpu host in qemu opts), so PAX detects PCID and enables strong
>> UDEREF. I will try with pax_weakuderef as soon as I get a chance to
>> reboot the VM.
>
> Fabulous "me too", I've got <cpu mode='host-model'> and guest have PCID
> available:
> dmesg |grep PCID
> [    0.020000] PAX: PCID detected
> [    0.020000] PAX: PCID detected
> [    0.020000] PAX: PCID detected
>
>
> Snip from cpuinfo of guest:
> processor       : 2
> vendor_id       : GenuineIntel
> cpu family      : 6
> model           : 42
> model name      : Intel Xeon E312xx (Sandy Bridge)
> stepping        : 1
> microcode       : 0x1
> cpu MHz         : 3292.514
> cache size      : 4096 KB
> physical id     : 2
> siblings        : 1
> core id         : 0
> cpu cores       : 1
> apicid          : 2
> initial apicid  : 2
> fpu             : yes
> fpu_exception   : yes
> cpuid level     : 13
> wp              : yes
> flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge
> mca cmov pat pse36 clflush mmx fxsr sse sse2 ss syscall nx rdtscp lm
> constant_tsc arch_perfmon rep_good nopl eagerfpu pni pclmulqdq ssse3
> cx16 pcid sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes xsave avx
> f16c rdrand hypervisor lahf_lm xsaveopt fsgsbase smep erms
> bogomips        : 6585.02
> clflush size    : 64
> cache_alignment : 64
> address sizes   : 40 bits physical, 48 bits virtual
> power management:
>
>

We should be doing this in a bug report.  I'll cc-pipacs.

-- 
Anthony G. Basile, Ph. D.
Chair of Information Technology
D'Youville College
Buffalo, NY 14201
(716) 829-8197