From: Shreeya Patel shreeya.patel@collabora.com
commit 5467801f1fcbdc46bc7298a84dbf3ca1ff2a7320 upstream.
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: Shreeya Patel shreeya.patel@collabora.com Cc: stable@vger.kernel.org Reviewed-by: Andy Shevchenko andy.shevchenko@gmail.com Reviewed-by: Linus Walleij linus.walleij@linaro.org Signed-off-by: Bartosz Golaszewski brgl@bgdev.pl Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/gpio/gpiolib.c | 19 +++++++++++++++++++ include/linux/gpio/driver.h | 9 +++++++++ 2 files changed, 28 insertions(+)
--- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -1411,6 +1411,16 @@ static int gpiochip_to_irq(struct gpio_c { 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)) return -ENXIO;
@@ -1604,6 +1614,15 @@ static int gpiochip_add_irqchip(struct g
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; }
--- a/include/linux/gpio/driver.h +++ b/include/linux/gpio/driver.h @@ -225,6 +225,15 @@ struct gpio_irq_chip { unsigned int ngpios);
/** + * @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; + + /** * @valid_mask: * * If not %NULL holds bitmask of GPIOs which are valid to be included