Commit 5467801f authored by Shreeya Patel's avatar Shreeya Patel Committed by Bartosz Golaszewski

gpio: Restrict usage of GPIO chip irq members before initialization

GPIO chip 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.

Following are the logs for reference :-

kernel: Call Trace:
kernel:  gpiod_to_irq+0x53/0x70
kernel:  acpi_dev_gpio_irq_get_by+0x113/0x1f0
kernel:  i2c_acpi_get_irq+0xc0/0xd0
kernel:  i2c_device_probe+0x28a/0x2a0
kernel:  really_probe+0xf2/0x460
kernel: RIP: 0010:gpiochip_to_irq+0x47/0xc0

To avoid such scenarios, restrict usage of GPIO chip irq members before
they are completely initialized.
Signed-off-by: default avatarShreeya Patel <shreeya.patel@collabora.com>
Cc: stable@vger.kernel.org
Reviewed-by: default avatarAndy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: default avatarLinus Walleij <linus.walleij@linaro.org>
Signed-off-by: default avatarBartosz Golaszewski <brgl@bgdev.pl>
parent 31231092
...@@ -1404,6 +1404,16 @@ static int gpiochip_to_irq(struct gpio_chip *gc, unsigned int offset) ...@@ -1404,6 +1404,16 @@ static int gpiochip_to_irq(struct gpio_chip *gc, unsigned int offset)
{ {
struct irq_domain *domain = gc->irq.domain; struct irq_domain *domain = gc->irq.domain;
#ifdef CONFIG_GPIOLIB_IRQCHIP
/*
* Avoid race condition with other code, which tries to lookup
* an IRQ before the irqchip has been properly registered,
* i.e. while gpiochip is still being brought up.
*/
if (!gc->irq.initialized)
return -EPROBE_DEFER;
#endif
if (!gpiochip_irqchip_irq_valid(gc, offset)) if (!gpiochip_irqchip_irq_valid(gc, offset))
return -ENXIO; return -ENXIO;
...@@ -1593,6 +1603,15 @@ static int gpiochip_add_irqchip(struct gpio_chip *gc, ...@@ -1593,6 +1603,15 @@ static int gpiochip_add_irqchip(struct gpio_chip *gc,
acpi_gpiochip_request_interrupts(gc); acpi_gpiochip_request_interrupts(gc);
/*
* Using barrier() here to prevent compiler from reordering
* gc->irq.initialized before initialization of above
* GPIO chip irq members.
*/
barrier();
gc->irq.initialized = true;
return 0; return 0;
} }
......
...@@ -221,6 +221,15 @@ struct gpio_irq_chip { ...@@ -221,6 +221,15 @@ struct gpio_irq_chip {
*/ */
bool per_parent_data; bool per_parent_data;
/**
* @initialized:
*
* Flag to track GPIO chip irq member's initialization.
* This flag will make sure GPIO chip irq members are not used
* before they are initialized.
*/
bool initialized;
/** /**
* @init_hw: optional routine to initialize hardware before * @init_hw: optional routine to initialize hardware before
* an IRQ chip will be added. This is quite useful when * an IRQ chip will be added. This is quite useful when
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment