Bug 2559678 (CVE-2026-98946)

Summary: CVE-2026-98946 kernel: kernel: Denial of Service via improper interrupt handling in drm/vc4
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's drm/vc4 graphics driver. During runtime power suspend transitions, the driver does not properly disable hardware interrupts before powering down the device. A local user triggering power transitions could cause interrupt handlers to execute while the hardware is unpowered, resulting in invalid register reads and improper background task scheduling. This flaw may lead to system instability or a Denial of Service (DoS).
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-10-23 13:00:16 UTC 
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.