diff options
| author | Shreeya Patel <shreeya.patel@collabora.com> | 2022-03-21 19:02:41 +0530 |
|---|---|---|
| committer | Bartosz Golaszewski <brgl@bgdev.pl> | 2022-04-04 14:41:34 +0200 |
| commit | 5467801f1fcbdc46bc7298a84dbf3ca1ff2a7320 (patch) | |
| tree | a32186986097a33e9836e207409aacdf72e5c348 | |
| parent | 3123109284176b1532874591f7c81f3837bbdc17 (diff) | |
| download | linux-5467801f1fcbdc46bc7298a84dbf3ca1ff2a7320.tar.bz2 | |
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: 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>
| -rw-r--r-- | drivers/gpio/gpiolib.c | 19 | ||||
| -rw-r--r-- | include/linux/gpio/driver.h | 9 |
2 files changed, 28 insertions, 0 deletions
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index e59884cc12a7..085348e08986 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -1404,6 +1404,16 @@ static int gpiochip_to_irq(struct gpio_chip *gc, unsigned int offset) { 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; @@ -1593,6 +1603,15 @@ static int gpiochip_add_irqchip(struct gpio_chip *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; } diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h index 98c93510640e..874aabd270c9 100644 --- a/include/linux/gpio/driver.h +++ b/include/linux/gpio/driver.h @@ -222,6 +222,15 @@ struct gpio_irq_chip { 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 * an IRQ chip will be added. This is quite useful when * a particular driver wants to clear IRQ related registers |