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Medium severity5.5NVD Advisory· Published Apr 5, 2024· Updated May 12, 2026

CVE-2024-27437

CVE-2024-27437

Description

In the Linux kernel, the following vulnerability has been resolved:

vfio/pci: Disable auto-enable of exclusive INTx IRQ

Currently for devices requiring masking at the irqchip for INTx, ie. devices without DisINTx support, the IRQ is enabled in request_irq() and subsequently disabled as necessary to align with the masked status flag. This presents a window where the interrupt could fire between these events, resulting in the IRQ incrementing the disable depth twice. This would be unrecoverable for a user since the masked flag prevents nested enables through vfio.

Instead, invert the logic using IRQF_NO_AUTOEN such that exclusive INTx is never auto-enabled, then unmask as required.

AI Insight

LLM-synthesized narrative grounded in this CVE's description and references.

In the Linux kernel, a race window in VFIO PCI INTx handling could cause an interrupt to be double-disabled, leading to an unrecoverable state for the user.

A vulnerability exists in the Linux kernel's VFIO PCI subsystem (CVE-2024-27437) where the exclusive INTx IRQ for devices requiring interrupt masking at the irqchip (devices without DisINTx support) was incorrectly auto-enabled. During request_irq(), the interrupt was enabled, then immediately disabled to match the masked status flag, creating a race window where an interrupt could fire before the disable, causing the IRQ handler to increment the disable depth twice [1]. This double-disable leads to an unrecoverable state for the user since the masked flag prevents nested enables through vfio.

An attacker with local access and the ability to trigger VFIO interrupt activity could exploit this race condition. The attack requires the presence of an affected VFIO device that lacks DisINTx support, and the attacker must be able to manipulate the timing of interrupt delivery. No special privileges beyond those needed to interact with VFIO devices are required, but the race is narrow and difficult to trigger reliably [1].

If successfully exploited, the vulnerability results in a denial of service (DoS) by leaving the interrupt line in a permanently disabled state. The user is unable to re-enable the interrupt through normal VFIO operations, making the device unusable until the system is rebooted. This could impact system availability, especially in virtualized environments where VFIO passthrough is used [1].

The fix, merged into the Linux kernel stable branches, inverts the logic by using the IRQF_NO_AUTOEN flag so that exclusive INTx is never auto-enabled, then unmasked as needed, eliminating the race window entirely [1]. Users should apply the latest kernel updates from their distribution. The vulnerability is also listed as affecting the SIMATIC S7-1500 TM MFP GNU/Linux subsystem (SSA-265688), which includes this CVE among many others [2]. No workarounds are documented; patching is the recommended mitigation.

References
  1. SSA-265688
  2. Making sure you're not a bot!

AI Insight generated on May 20, 2026. Synthesized from this CVE's description and the cited reference URLs; citations are validated against the source bundle.

Affected products

120

Patches

0

No patches discovered yet.

Vulnerability mechanics

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References

10

News mentions

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