Spectre Variant 2 on CentoS 6.8

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polax
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Spectre Variant 2 on CentoS 6.8

Post by polax » 2018/03/09 04:14:54

Hi,
I have updated my CentOS 6 with "yum update" and restarted, but spectre-meltdown-checker is showing vulnerability to Variant 2:
https://puu.sh/zDIam/2b3c438169.png

How can I fix it?

chemal
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Re: Spectre Variant 2 on CentoS 6.8

Post by chemal » 2018/03/09 05:40:55

Your kernel is compiled with IBRS but your CPU microcode is lacking support to successfully mitigate the vulnerability.

Ask Intel for a microcode update or your hardware vendor for a BIOS update that includes this microcode update.

Up to now, Intel has only come up with a microcode update for Skylake CPUs and you can only get it if your hardware vendor offers a BIOS update including it.

It is not included here: https://downloadcenter.intel.com/downlo ... -Data-File

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TrevorH
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Re: Spectre Variant 2 on CentoS 6.8

Post by TrevorH » 2018/03/09 14:33:13

Moved to CentOS 6 Security forum.
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tsrini
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Re: Spectre Variant 2 on CentoS 6.8

Post by tsrini » 2018/08/16 11:03:56

Hi,

I'm using Cent OS 6.5. With the latest kernel and dracut patches below, it seems all the 3 variants (Spectre Variant 1 & 2, Meltdown) are fixed.

kernel-2.6.32-754.2.1.el6.x86_64
kernel-firmware-2.6.32-754.2.1.el6.noarch

dracut-kernel-004-411.el6.noarch
dracut-004-411.el6.noarch

The spectre checker script shows the below,

Code: Select all

Spectre and Meltdown mitigation detection tool v0.36+

Checking for vulnerabilities on current system
Kernel is Linux 2.6.32-754.3.5.el6.x86_64 #1 SMP Tue Aug 14 20:46:41 UTC 2018 x86_64
CPU is Intel(R) Xeon(R) CPU           L5518  @ 2.13GHz

Hardware check
* Hardware support (CPU microcode) for mitigation techniques
  * Indirect Branch Restricted Speculation (IBRS)
    * SPEC_CTRL MSR is available:  NO
    * CPU indicates IBRS capability:  NO
  * Indirect Branch Prediction Barrier (IBPB)
    * PRED_CMD MSR is available:  NO
    * CPU indicates IBPB capability:  NO
  * Single Thread Indirect Branch Predictors (STIBP)
    * SPEC_CTRL MSR is available:  NO
    * CPU indicates STIBP capability:  NO
  * Enhanced IBRS (IBRS_ALL)
    * CPU indicates ARCH_CAPABILITIES MSR availability:  NO
    * ARCH_CAPABILITIES MSR advertises IBRS_ALL capability:  NO
  * CPU explicitly indicates not being vulnerable to Meltdown (RDCL_NO):  NO
  * CPU microcode is known to cause stability problems:  NO  (model 26 stepping 5 ucode 17)
* CPU vulnerability to the three speculative execution attack variants
  * Vulnerable to Variant 1:  YES
  * Vulnerable to Variant 2:  YES
  * Vulnerable to Variant 3:  YES

CVE-2017-5753 [bounds check bypass] aka 'Spectre Variant 1'
* Mitigated according to the /sys interface:  YES  (kernel confirms that the mitigation is active)
* Kernel has array_index_mask_nospec:  YES  (1 occurence(s) found of 64 bits array_index_mask_nospec())
* Kernel has the Red Hat/Ubuntu patch:  YES
[b]> STATUS:  NOT VULNERABLE  (Mitigation: Load fences)[/b]

CVE-2017-5715 [branch target injection] aka 'Spectre Variant 2'
* Mitigated according to the /sys interface:  YES  (kernel confirms that the mitigation is active)
* Mitigation 1
  * Kernel is compiled with IBRS/IBPB support:  YES
  * Currently enabled features
    * IBRS enabled for Kernel space:  NO
    * IBRS enabled for User space:  NO
    * IBPB enabled:  NO
* Mitigation 2
  * Kernel has branch predictor hardening (ARM):  NO
  * Kernel compiled with retpoline option:  YES
  * Kernel compiled with a retpoline-aware compiler:  YES  (kernel reports full retpoline compilation)
[b]> STATUS:  NOT VULNERABLE  (Mitigation: Full retpoline)[/b]

CVE-2017-5754 [rogue data cache load] aka 'Meltdown' aka 'Variant 3'
* Mitigated according to the /sys interface:  YES  (kernel confirms that the mitigation is active)
* Kernel supports Page Table Isolation (PTI):  YES  (found 'CONFIG_PAGE_TABLE_ISOLATION=y')
* PTI enabled and active:  YES
* Running as a Xen PV DomU:  NO
[b]> STATUS:  NOT VULNERABLE  (Mitigation: PTI)[/b]

A false sense of security is worse than no security at all, see --disclaimer
[root@c3bng-src2 spectre-meltdown-checker-master]#
Is the Spectre Variant 2 fixed in recent kernel/dracut patches?

Regards,
Srini

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TrevorH
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Re: Spectre Variant 2 on CentoS 6.8

Post by TrevorH » 2018/08/16 12:00:36

Don't use 6.5, it's more than 5 years old and riddled with security bugs. Run a yum update to get the rest of your server up to date. There are many much more important and exploitable vulnerabilities in 6.5 than just meltdown/spectre.
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tsrini
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Re: Spectre Variant 2 on CentoS 6.8

Post by tsrini » 2018/08/17 08:26:41

Yes, we have CentOS upgrade in pipeline and it involves huge effort in porting our product/deployment. We will be working on it.

Just to understand the recent changes in the kernel patches, earlier version of kernel & dracut patches (kernel-2.6.32-696.18.7.el6.x86_64,
kernel-firmware-2.6.32-696.18.7.el6.noarch, dracut-kernel-004-409.el6_8.2.noarch, dracut-004-409.el6_8.2.noarch) haven't fixed the Spectre Variant 2 but the recent one fixed it (without any BIOS / Intel patch).

Is Spectre Variant 2 specifically addressed in recent kernel / dracut patches?

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TrevorH
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Re: Spectre Variant 2 on CentoS 6.8

Post by TrevorH » 2018/08/17 09:08:48

viewtopic.php?f=17&t=65800

As far as I know, nothing has changed and you need updated microcode to fix everything (that's currently publicly known).
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tsrini
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Re: Spectre Variant 2 on CentoS 6.8

Post by tsrini » 2018/08/17 11:12:56

Ok Thank you.

polax
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Re: Spectre Variant 2 on CentoS 6.8

Post by polax » 2018/08/17 18:46:38

Does a "yum update" fix this? If not, where can I see the list of micro code and any instruction to apply them?

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