From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-cve-announce@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@kernel.org>
Subject: CVE-2026-80896: mshv: Fix race in mshv_irqfd_deassign
Date: Fri, 4 Sep 2026 19:09:37 +0200 [thread overview]
Message-ID: <2026090430-CVE-2026-80896-97e0@gregkh> (raw)
From: Greg Kroah-Hartman <gregkh@kernel.org>
Description
===========
In the Linux kernel, the following vulnerability has been resolved:
mshv: Fix race in mshv_irqfd_deassign
mshv_irqfd_deactivate() and the hlist traversal of pt_irqfds_list
require pt->pt_irqfds_lock to be held, but mshv_irqfd_deassign()
omits it. This races with the EPOLLHUP path in mshv_irqfd_wakeup(),
which does take the lock before calling mshv_irqfd_deactivate().
Additionally, mshv_irqfd_deactivate() uses hlist_del() which poisons
the node pointers rather than resetting them. Since
mshv_irqfd_is_active() relies on hlist_unhashed() (checks pprev ==
NULL), a poisoned node still appears active. If a concurrent path calls
mshv_irqfd_deactivate() again on the same irqfd, the guard fails to
prevent a double hlist_del() on poisoned pointers.
Fix both issues:
- Add the missing spin_lock_irq/spin_unlock_irq around the list
traversal in mshv_irqfd_deassign(), matching mshv_irqfd_release().
- Use hlist_del_init() instead of hlist_del() so the node is properly
marked as unhashed after removal, making the is_active guard reliable.
The Linux kernel CVE team has assigned CVE-2026-80896 to this issue.
Affected and fixed versions
===========================
Issue introduced in 6.15 with commit 621191d709b14882270dfd8ea5d7d6cdfebe2c35 and fixed in 6.18.44 with commit 72a90ce4918b5a2d4820fe20677ba9af780d8826
Issue introduced in 6.15 with commit 621191d709b14882270dfd8ea5d7d6cdfebe2c35 and fixed in 7.1.8 with commit 4529a41a675b96e0f876eef1cc93a31a57cb4d18
Issue introduced in 6.15 with commit 621191d709b14882270dfd8ea5d7d6cdfebe2c35 and fixed in 7.2 with commit 0762262ac3e70f65b3bb843fe892f8bac1562d08
Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.
Unaffected versions might change over time as fixes are backported to
older supported kernel versions. The official CVE entry at
https://cve.org/CVERecord/?id=CVE-2026-80896
will be updated if fixes are backported, please check that for the most
up to date information about this issue.
Affected files
==============
The file(s) affected by this issue are:
drivers/hv/mshv_eventfd.c
Mitigation
==========
The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes. Individual
changes are never tested alone, but rather are part of a larger kernel
release. Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all. If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
https://git.kernel.org/stable/c/72a90ce4918b5a2d4820fe20677ba9af780d8826
https://git.kernel.org/stable/c/4529a41a675b96e0f876eef1cc93a31a57cb4d18
https://git.kernel.org/stable/c/0762262ac3e70f65b3bb843fe892f8bac1562d08
reply other threads:[~2026-09-04 17:15 UTC|newest]
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