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    <title>Most recent entries from all</title>
    <link>https://vulnerability.circl.lu</link>
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    <lastBuildDate>Tue, 29 Sep 2026 20:16:09 +0000</lastBuildDate>
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      <title>CVE-2026-89957 — s390/vfio-ap: Fix hot-unplug skipped when last AP adapter or domain removed</title>
      <link>https://vulnerability.circl.lu/vuln/cve-2026-89957</link>
      <description>&lt;p&gt;&lt;strong&gt;Affected:&lt;/strong&gt; Linux&lt;/p&gt;
&lt;p&gt;In the Linux kernel, the following vulnerability has been resolved:&lt;/p&gt;
&lt;p&gt;s390/vfio-ap: Fix hot-unplug skipped when last AP adapter or domain removed&lt;/p&gt;
&lt;p&gt;The vfio_ap_mdev_hot_unplug_cfg() function uses the return value of
bitmap_andnot() to determine whether the guest APCB needs to be updated.
However, bitmap_andnot() returns false when the resulting destination
bitmap is empty. This means that if the only adapter, domain or control
domain assigned to an mdev is removed from the host&amp;#39;s AP configuration,
the bit is correctly cleared from the shadow APCB, but bitmap_andnot()
returns false because the result is an empty bitmap. Consequently,
do_hotplug remains 0 and vfio_ap_mdev_update_guest_apcb() is never called,
leaving the KVM guest with stale hardware access to the unplugged AP
devices.&lt;/p&gt;
&lt;p&gt;Fix this by replacing the bitmap_andnot() return value check with
bitmap_intersects() to determine whether the shadow APCB actually
overlaps with the removal mask. If there is an intersection, call
bitmap_andnot() solely for its side effect of clearing the bits, then
unconditionally set do_hotplug to trigger the guest APCB update.&lt;/p&gt;</description>
      <content:encoded>&lt;p&gt;&lt;strong&gt;Affected:&lt;/strong&gt; Linux&lt;/p&gt;
&lt;p&gt;In the Linux kernel, the following vulnerability has been resolved:&lt;/p&gt;
&lt;p&gt;s390/vfio-ap: Fix hot-unplug skipped when last AP adapter or domain removed&lt;/p&gt;
&lt;p&gt;The vfio_ap_mdev_hot_unplug_cfg() function uses the return value of
bitmap_andnot() to determine whether the guest APCB needs to be updated.
However, bitmap_andnot() returns false when the resulting destination
bitmap is empty. This means that if the only adapter, domain or control
domain assigned to an mdev is removed from the host&amp;#39;s AP configuration,
the bit is correctly cleared from the shadow APCB, but bitmap_andnot()
returns false because the result is an empty bitmap. Consequently,
do_hotplug remains 0 and vfio_ap_mdev_update_guest_apcb() is never called,
leaving the KVM guest with stale hardware access to the unplugged AP
devices.&lt;/p&gt;
&lt;p&gt;Fix this by replacing the bitmap_andnot() return value check with
bitmap_intersects() to determine whether the shadow APCB actually
overlaps with the removal mask. If there is an intersection, call
bitmap_andnot() solely for its side effect of clearing the bits, then
unconditionally set do_hotplug to trigger the guest APCB update.&lt;/p&gt;</content:encoded>
      <guid isPermaLink="false">https://vulnerability.circl.lu/vuln/cve-2026-89957</guid>
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