Changeset 78632 in vbox for trunk/doc/manual/en_US

Timestamp:

May 21, 2019 1:56:11 PM (6 years ago)

Author:

vboxsync

Message:

Forward ported 130474,130475,130477,130479. bugref:9453

Location:

trunk

Files:

• . (modified) (1 prop)
• doc/manual/en_US/user_Security.xml (modified) (1 diff)

trunk

@@ -9 +9 @@
 /branches/VBox-5.1:112367,115992,116543,116550,116568,116573
 /branches/VBox-5.2:119536,120083,120099,120213,120221,120239,123597-123598,123600-123601,123755,124260,124263,124271,124273,124277-124279,124284-124286,124288-124290,125768,125779-125780,125812
+/branches/VBox-6.0:130474-130475,130477,130479
 /branches/aeichner/vbox-chromium-cleanup:129816,129818-129851,129853-129861,129871-129872,129876,129880,129882,130013-130015,130036,130094-130095
 /branches/andy/draganddrop:90781-91268

@@ -9 +9 @@
 /branches/VBox-5.1:112367,115992,116543,116550,116568,116573
 /branches/VBox-5.2:119536,120083,120099,120213,120221,120239,123597-123598,123600-123601,123755,124260,124263,124271,124273,124277-124279,124284-124286,124288-124290,125768,125779-125780,125812
+/branches/VBox-6.0:130474-130475,130477,130479
 /branches/aeichner/vbox-chromium-cleanup:129816,129818-129851,129853-129861,129871-129872,129876,129880,129882,130013-130015,130036,130094-130095
 /branches/andy/draganddrop:90781-91268

trunk/doc/manual/en_US/user_Security.xml

@@ -637 +637 @@
     </sect2>
 
+    <sect2 id="sec-rec-cve-2018-12126-et-al">
+
+      <title>CVE-2018-12126, CVE-2018-12127, CVE-2018-12130, CVE-2019-11091</title>
+
+      <para>
+        These security issues affect a range of Intel CPUs starting with
+        Nehalem.  The CVE-2018-12130 also affects some Atom Silvermont,
+        Atom Airmont, and Knights family CPUs, however the scope is so limited
+        that the host OS should deal with it for us and VBox therefore not
+        be affected (leaks only happens when entering and leaving C states).
+      </para>
+
+      <para>
+        Mitigation option:
+      </para>
+
+      <sect3>
+
+        <title>Buffer overwriting and disabling HT</title>
+
+        <para>
+          First, up to date CPU microcode is a prerequisite for the buffer
+          overwriting (clearing) mitigations.  Some host OSes may install
+          these automatically, though it has traditionally been a task best
+          performed by the system firmware.  So, please check with your
+          system / mainboard manufacturer for the latest firmware update.
+        </para>
+
+        <para>
+          This mitigation aims at removing potentially sensitive data from
+          the affected buffers before running guest code.  Since this means
+          additional work each time the guest is scheduled, there might be
+          some performance side effects.
+        </para>
+
+        <para>
+          We recommend disabling hyper threading on host affected by
+          CVE-2018-12126 and CVE-2018-12127 because the affected sets of
+          buffers are normally shared between thread pairs and therefore
+          cause leaks between the threads. This is traditionally done from
+          the firmware setup, but some OSes also offers ways disable HT. In
+          some cases it may be disabled by default, but please verify as the
+          effectiveness of the mitigation depends on it.
+        </para>
+
+        <para>
+          The default action taken by VirtualBox is to clear the affected
+          buffers when a thread is scheduled to execute guest code, rather
+          than on each VM entry. This reduces the performance impact, while
+          making the assumption that the host OS will not handle security
+          sensitive data from interrupt handlers and similar without taking
+          precautions.
+        </para>
+
+        <para>
+          A more aggressive flushing option is provided via the
+          VBoxManage modifyvm option
+          <computeroutput>--mds-clear-on-vm-entry</computeroutput>. When
+          enabled the affected buffers will be cleared on every VM entry.
+          The performance impact is greater than with the default option,
+          though this of course depends on the workload.  Workloads producing
+          a lot of VM exits (like networking, VGA access, and similiar) will
+          probably be most impacted.
+        </para>
+
+        <para>
+          For users not concerned by this security issue, the default
+          mitigation can be disabled using
+        </para>
+
+        <para>
+          <computeroutput>VBoxManage modifyvm name --mds-clear-on-sched
+          off</computeroutput>
+        </para>
+
+      </sect3>
+
+    </sect2>
+
   </sect1>
 

@@ -9 +9 @@
 /branches/VBox-5.1:112367,115992,116543,116550,116568,116573
 /branches/VBox-5.2:119536,120083,120099,120213,120221,120239,123597-123598,123600-123601,123755,124260,124263,124271,124273,124277-124279,124284-124286,124288-124290,125768,125779-125780,125812
+/branches/VBox-6.0:130474-130475,130477,130479
 /branches/aeichner/vbox-chromium-cleanup:129816,129818-129851,129853-129861,129871-129872,129876,129880,129882,130013-130015,130036,130094-130095
 /branches/andy/draganddrop:90781-91268