Bug 2495947 (CVE-2026-53326)

Summary: CVE-2026-53326 kernel: debugobjects: Don't call fill_pool() in early boot hardirq context
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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Priority: low    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's debugobjects subsystem. During early boot on a debug PREEMPT_RT kernel on an ARM64 system, interrupts can occur before the scheduler is fully enabled. In this specific window, the hard interrupt context handler may attempt to fill a pool, which can lead to a deadlock. This issue can cause the system to become unresponsive.
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Description OSIDB Bzimport 2026-07-01 14:02:56 UTC
In the Linux kernel, the following vulnerability has been resolved:

debugobjects: Don't call fill_pool() in early boot hardirq context

When booting a debug PREEMPT_RT kernel on an ARM64 system, a "inconsistent
{HARDIRQ-ON-W} -> {IN-HARDIRQ-W} usage" lockdep warning message was
reported to the console.

During early boot, interrupts are enabled before the scheduler is
enabled. In this window (before SYSTEM_SCHEDULING is set) interrupts can
fire and in the hard interrupt context handler attempt to fill the pool

This can lead to a deadlock when the interrupt occurred when the interrupt
hits a region which holds a lock that is required to be taken in the
allocation path.

Add a new can_fill_pool() helper and reorder the exception rule and forbid
this scenario by excluding allocations from hard interrupt context.

Comment 1 Mauro Matteo Cascella 2026-07-01 16:56:41 UTC
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026070140-CVE-2026-53326-8836@gregkh/T