CVE-2026-98094: staging: fbtft: make dirty_lock IRQ-safe

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-25 · updated 2026-10-23
Weakness: CWE-667

Description

In the Linux kernel, the following vulnerability has been resolved: staging: fbtft: make dirty_lock IRQ-safe fbtft_mkdirty() can be reached from the fbcon rendering path while processing printk() in hardirq context. Meanwhile, dirty_lock is also taken by fbtft_deferred_io() in workqueue context with local interrupts enabled. Lockdep reports a possible IRQ lock inversion involving dirty_lock and console_owner. A hardirq can interrupt a CPU holding dirty_lock and enter the console rendering path, which can attempt to acquire dirty_lock again. The following lockdep report was observed on an RK3566 system with CONFIG_PROVE_LOCKING enabled: WARNING: possible irq lock inversion dependency detected swapper/2/0 just changed the state of lock: (console_owner){-...}-{0:0} but this lock took another, HARDIRQ-unsafe lock in the past: (&par->dirty_lock){+.+.}-{2:2} CPU0 CPU1 ---- ---- lock(&par->dirty_lock); local_irq_disable(); lock(console_owner); lock(&par->dirty_lock); <Interrupt> lock(console_owner); *** DEADLOCK *** Use spin_lock_irqsave() for fbtft_mkdirty() and spin_lock_irq() for fbtft_deferred_io(). They only access the dirty line range, so the IRQ-off regions remain short.

Affected products

Linux kernel: from 4.0 before 5.10.271; from 5.11 before 5.15.222; from 5.16 before 6.1.189; from 6.2 before 6.6.158; from 6.7 before 6.12.111; from 6.13 before 6.18.53 — fixed in 5.10.271, 5.15.222, 6.1.189, 6.12.111, 6.18.53, 6.6.158

How to fix

Upgrade to a fixed version: Linux kernel 5.10.271, 5.15.222, 6.1.189, 6.12.111. Check the vendor advisory for mitigations.

References

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