CVE-2026-98094

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.