Linux Kernel up to 7.2.10 VC4 DRM Driver drm/vc4 vc4_irq_disable race condition

Summaryinfo

A vulnerability was found in Linux Kernel up to 7.2.10. It has been rated as problematic. This affects the function vc4_irq_disable of the file drm/vc4 of the component VC4 DRM Driver. This manipulation causes race condition. The identification of this vulnerability is CVE-2026-98946. The attack can only be executed locally. There is no exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability classified as problematic was found in Linux Kernel up to 7.2.10. Affected by this vulnerability is the function vc4_irq_disable of the file drm/vc4 of the component VC4 DRM Driver. The manipulation with an unknown input leads to a race condition vulnerability. The CWE definition for the vulnerability is CWE-362. The product contains a code sequence that can run concurrently with other code, and the code sequence requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence that is operating concurrently. As an impact it is known to affect integrity, and availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: drm/vc4: Disable the V3D interrupt across runtime suspend vc4_irq_disable() masks the V3D interrupt sources and then calls synchronize_irq() before the V3D is powered down. However, by itself, this is not enough to quiesce the interrupt handler. synchronize_irq() waits for handlers that have already set IRQD_IRQ_INPROGRESS, and for irqchips reporting IRQCHIP_STATE_ACTIVE. A GIC interrupt chip is able to mark an interrupt active as soon as a CPU acknowledges it, so there these checks cover the whole dispatch path. On RPi 0-3, however, the interrupt controller is ARMCTRL, which has no active state. A CPU that has read the hwirq out of the pending register but has not yet reached handle_level_irq() stays invisible to synchronize_irq(). During a power transition, vc4_irq() may therefore run after the power domain is off, where every V3D register read will return 0xdeadbeef. 0xdeadbeef has FLDONE, FRDONE and OUTOMEM set. This problem doesn't trigger NULL pointer dereference issues only because the functions vc4_irq_finish_bin_job() and vc4_irq_finish_render_job() return early when there is no job pointer, but OUTOMEM is still able to schedule vc4_overflow_mem_work() after vc4_irq_disable() has already cancelled it. Therefore, fix the spurious interrupts by disabling the interrupt line across the PM transition. To preserve the enable/disable balance, move vc4_irq_install() and request the IRQ line disabled before the first runtime resume.

It is possible to read the advisory at git.kernel.org. This vulnerability is known as CVE-2026-98946 since 09/25/2026. The exploitation appears to be easy. Attacking locally is a requirement. Technical details of the vulnerability are known, but there is no available exploit.

Upgrading to version 7.2.11 eliminates this vulnerability. Applying the patch e81402c3d42041356cb7978510ebab997bc8d411/6abc8e4dcfbc1d26a94c0ac037dfb3716f686b1f is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 7.2.0
• 7.2.1
• 7.2.2
• 7.2.3
• 7.2.4
• 7.2.5
• 7.2.6
• 7.2.7
• 7.2.8
• 7.2.9
• 7.2.10

License

• open-source

Website

• Vendor: https://www.kernel.org/

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