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             AUSCERT External Security Bulletin Redistribution

                         Security updates for kvm
                               26 April 2018


        AusCERT Security Bulletin Summary

Product:           kvm
Publisher:         SUSE
Operating System:  SUSE
Impact/Access:     Execute Arbitrary Code/Commands -- Existing Account
                   Access Privileged Data          -- Existing Account
                   Denial of Service               -- Existing Account
Resolution:        Patch/Upgrade
CVE Names:         CVE-2018-7550 CVE-2018-5683 CVE-2017-18030

Reference:         ASB-2018.0009

Original Bulletin: 

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   SUSE Security Update: Security update for kvm

Announcement ID:    SUSE-SU-2018:1077-1
Rating:             important
References:         #1068032 #1076114 #1076179 #1082276 #1083291 
Cross-References:   CVE-2017-18030 CVE-2017-5715 CVE-2018-5683
Affected Products:
                    SUSE Linux Enterprise Server 11-SP4

   An update that solves four vulnerabilities and has one
   errata is now available.


   This update for kvm fixes the following issues:

   - This update has the next round of Spectre v2 related patches, which now
     integrates with corresponding changes in libvirt. A January 2018 release
     of qemu initially addressed the Spectre v2 vulnerability for KVM guests
     by exposing the spec-ctrl feature for all x86 vcpu types, which was the
     quick and dirty approach, but not the proper solution. We remove that
     initial patch and now rely on patches from upstream. This update defines
     spec_ctrl and ibpb cpu feature flags as well as new cpu models which are
     of existing models with either -IBRS or -IBPB added to the end of the
      model name. These new vcpu models explicitly include the new
      feature(s), whereas the feature flags can be added to the cpu parameter
      as with other features. In short, for continued Spectre v2 protection,
      ensure that either the appropriate cpu feature flag is added to the
      QEMU command-line, or one of the new cpu models is used. Although
      migration from older versions is supported, the new cpu features won't
      be properly exposed to the guest until it is restarted with the cpu
      features explicitly added. A reboot is insufficient.
   - A warning patch is added which attempts to detect a migration from a
     qemu version which had the quick and dirty fix (it only detects certain
     cases, but hopefully is helpful.) For additional information on Spectre
     v2 as it relates to QEMU, see:
     (CVE-2017-5715 bsc#1068032)
   - A patch is added to continue to detect Spectre v2 mitigation features
     (as shown by cpuid), and if found provide that feature to guests, even
     if running on older KVM (kernel) versions which do not yet expose that
     feature to QEMU. (bsc#1082276) These two patches will be removed when we
     can reasonably assume everyone is running with the appropriate updates.

   - Security fixes for the following CVE issues: (bsc#1076114 CVE-2018-5683)
     (bsc#1083291 CVE-2018-7550)
   - This patch is already included, add here for CVE track (bsc#1076179

   - Toolchain changes have cause the built size of pxe-virtio.rom to exceed
     64K. Tweak rarely used strings in code to reduce size of the binary so
     it fits again.

   - Eliminate bogus use of CPUID_7_0_EDX_PRED_CMD which we've carried since
     the initial Spectre v2 patch was added. EDX bit 27 of CPUID Leaf 07H,
     Sub-leaf 0 provides status on STIBP, and not the PRED_CMD MSR. Exposing
     the STIBP CPUID feature bit to the guest is wrong in general, since the
     VM doesn't directly control the scheduling of physical hyperthreads.
     This is left strictly to the L0 hypervisor.

Patch Instructions:

   To install this SUSE Security Update use the SUSE recommended installation methods
   like YaST online_update or "zypper patch".

   Alternatively you can run the command listed for your product:

   - SUSE Linux Enterprise Server 11-SP4:

      zypper in -t patch slessp4-kvm-13571=1

Package List:

   - SUSE Linux Enterprise Server 11-SP4 (i586 s390x x86_64):




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