To: linux-kernel@vger.kernel.org Cc: Paul Walmsley paul.walmsley@sifive.com Cc: Samuel Holland samuel.holland@sifive.com Cc: stable@vger.kernel.org Cc: linux-riscv@lists.infradead.org Cc: Thomas Gleixner tglx@linutronix.de

According to the PLIC specification[1], global interrupt sources are assigned small unsigned integer identifiers beginning at the value 1. An interrupt ID of 0 is reserved to mean "no interrupt".

The current plic_irq_resume() and plic_irq_suspend() functions incorrectly starts the loop from index 0, which could access the reserved interrupt ID 0 register space. This fix changes the loop to start from index 1, skipping the reserved interrupt ID 0 as per the PLIC specification.

This prevents potential undefined behavior when accessing the reserved register space during suspend/resume cycles.

Fixes: e80f0b6a2cf3 ("irqchip/irq-sifive-plic: Add syscore callbacks for hibernation") Co-developed-by: Jia Wang wangjia@ultrarisc.com Signed-off-by: Jia Wang wangjia@ultrarisc.com Signed-off-by: Lucas Zampieri lzampier@redhat.com

[1] https://github.com/riscv/riscv-plic-spec/releases/tag/1.0.0 --- drivers/irqchip/irq-sifive-plic.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/irqchip/irq-sifive-plic.c b/drivers/irqchip/irq-sifive-plic.c index bf69a4802b71..1c2b4d2575ac 100644 --- a/drivers/irqchip/irq-sifive-plic.c +++ b/drivers/irqchip/irq-sifive-plic.c @@ -252,7 +252,7 @@ static int plic_irq_suspend(void)

priv = per_cpu_ptr(&plic_handlers, smp_processor_id())->priv;

- for (i = 0; i < priv->nr_irqs; i++) { + for (i = 1; i < priv->nr_irqs; i++) { __assign_bit(i, priv->prio_save, readl(priv->regs + PRIORITY_BASE + i * PRIORITY_PER_ID)); } @@ -283,7 +283,7 @@ static void plic_irq_resume(void)

priv = per_cpu_ptr(&plic_handlers, smp_processor_id())->priv;

- for (i = 0; i < priv->nr_irqs; i++) { + for (i = 1; i < priv->nr_irqs; i++) { index = BIT_WORD(i); writel((priv->prio_save[index] & BIT_MASK(i)) ? 1 : 0, priv->regs + PRIORITY_BASE + i * PRIORITY_PER_ID);