Re: [PATCH] gpio: Restrict usage of gc irq members before initialization
From: Andy Shevchenko
Date: Thu Mar 10 2022 - 09:55:29 EST
On Thu, Mar 10, 2022 at 3:22 PM Shreeya Patel
<shreeya.patel@xxxxxxxxxxxxx> wrote:
>
> gc irq members are exposed before they could be completely
> initialized and this leads to race conditions.
>
> One such issue was observed for the gc->irq.domain variable which
> was accessed through the I2C interface in gpiochip_to_irq() before
> it could be initialized by gpiochip_add_irqchip(). This resulted in
> Kernel NULL pointer dereference.
>
> To avoid such scenarios, restrict usage of gc irq members before
> they are completely initialized.
Fixes tag?
...
> +bool gc_irq_initialized;
Non-static?
Why is it global?
...
> @@ -1593,6 +1594,8 @@ static int gpiochip_add_irqchip(struct gpio_chip *gc,
>
> acpi_gpiochip_request_interrupts(gc);
>
> + gc_irq_initialized = true;
This is wrong. Imagine a system where you have more than one GPIO chip.
...
> - if (gc->to_irq) {
> + if (gc->to_irq && gc_irq_initialized) {
> int retirq = gc->to_irq(gc, offset);
Shouldn't it rather be something like
if (gc->to_irq) {
if (! ..._initialized)
return -EPROBE_DEFER;
...
}
?
--
With Best Regards,
Andy Shevchenko