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authorShreeya Patel <shreeya.patel@collabora.com>2022-03-21 19:02:41 +0530
committerBartosz Golaszewski <brgl@bgdev.pl>2022-04-04 14:41:34 +0200
commit5467801f1fcbdc46bc7298a84dbf3ca1ff2a7320 (patch)
treea32186986097a33e9836e207409aacdf72e5c348 /drivers/gpio
parent3123109284176b1532874591f7c81f3837bbdc17 (diff)
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>
Diffstat (limited to 'drivers/gpio')
-rw-r--r--drivers/gpio/gpiolib.c19
1 files changed, 19 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;
}