CVE-2026-80896

Summary

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.

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/72a90ce4918b5a2d4820fe20677ba9af780d8826
• https://git.kernel.org/stable/c/4529a41a675b96e0f876eef1cc93a31a57cb4d18
• https://git.kernel.org/stable/c/0762262ac3e70f65b3bb843fe892f8bac1562d08

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