Re: Is Debian Linux protected against the Meltdown and Spectre security flaws?

On 23 February 2018 at 16:14, Michael Fothergill <michael.fothergill@gmail.com> wrote:

On 23 February 2018 at 14:14, Michael Fothergill <michael.fothergill@gmail.com> wrote:

On 23 February 2018 at 14:05, mlnl <mlnl@mailbox.org> wrote:
Hi,

> Can it be true? A version of gcc that runs on stretch that will
> compile the latest fancy spectre fixes etc?

with latest vanilla kernel 4.15.4 and updated gcc-6:

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())
> STATUS: NOT VULNERABLE (Mitigation: __user pointer sanitization)

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: NO
* Currently enabled features
* IBRS enabled for Kernel space: NO
* IBRS enabled for User space: NO
* IBPB enabled: NO
* Mitigation 2
* Kernel compiled with retpoline option: YES
* Kernel compiled with a retpoline-aware compiler: YES (kernel
reports full retpoline compilation)
* Retpoline enabled: NO

Wot? How can retpoline not be enabled but the status is not vulnerable......

Sure enough, looking at the spectre meltdown checker on the kernel I am using in gentoo

shows the

retpoline is enabled and that the vulnerability status is "not vulnerable".

It's not recent enough a kernel to address the spectre variant 1 problem as far as I am aware.

Oh well...

Cheers MF

djt /home/mikef/spectre-meltdown-checker # ./spectre-meltdown-checker.sh
Spectre and Meltdown mitigation detection tool v0.32

Checking for vulnerabilities on current system
Kernel is Linux 4.14.15-gentoo #1 SMP Tue Jan 30 16:22:47 GMT 2018 x86_64
CPU is AMD A10-7850K Radeon R7, 12 Compute Cores 4C+8G

CVE-2017-5753 [bounds check bypass] aka 'Spectre Variant 1'
* Mitigated according to the /sys interface: NO (kernel confirms your system is vulnerable)
> STATUS: VULNERABLE (Vulnerable)

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
* Hardware support (CPU microcode)
    * 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
* Kernel is compiled with IBRS/IBPB support: NO
* Currently enabled features
    * IBRS enabled for Kernel space: NO
    * IBRS enabled for User space: NO
    * IBPB enabled: NO
* Mitigation 2
* Kernel compiled with retpoline option: YES
* Kernel compiled with a retpoline-aware compiler: YES (kernel reports full retpoline compilation)
* Retpoline enabled: YES
> STATUS: NOT VULNERABLE (Mitigation: Full AMD retpoline)

CVE-2017-5754 [rogue data cache load] aka 'Meltdown' aka 'Variant 3'
* Mitigated according to the /sys interface: YES (kernel confirms that your CPU is unaffected)
* Kernel supports Page Table Isolation (PTI): YES
* PTI enabled and active: NO
* Running under Xen PV (64 bits): NO
> STATUS: NOT VULNERABLE (your CPU vendor reported your CPU model as not vulnerable)

A false sense of security is worse than no security at all, see --disclaimer
djt /home/mikef/spectre-meltdown-checker #

> STATUS: NOT VULNERABLE (Mitigation: Full generic retpoline)

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
* PTI enabled and active: YES
* Running as a Xen PV DomU: NO
> STATUS: NOT VULNERABLE (Mitigation: PTI)

Absolutely whale harpooned it....

Great stuff.

Cheers

MF

grep bugs /proc/cpuinfo
bugs : cpu_meltdown spectre_v1 spectre_v2
model name : Intel(R) Core(TM) i5-4570 CPU @ 3.20GHz

stepping : 3

microcode : 0x22

--
mlnl