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gpio: Restrict usage of GPIO chip irq members before initialization 

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2071835
Tested: This is one of a series of patch sets to enable Arm SystemReady IR
 support in the kernel for NXP i.MX8 platforms.  This set updates GPIO
 support.  It has been tested via simple boot tests and by using the
 kernel GPIO tools to verify pins are being identified and can be used.

commit 5467801f1fcbdc46bc7298a84dbf3ca1ff2a7320
Author: Shreeya Patel <shreeya.patel@collabora.com>
Date:   Mon Mar 21 19:02:41 2022 +0530

    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>
    (cherry picked from commit 5467801f1fcbdc46bc7298a84dbf3ca1ff2a7320)

Signed-off-by: Al Stone <ahs3@redhat.com>
This commit is contained in:
Al Stone 2022-08-24 13:28:45 -06:00
parent 87115178ac
commit 550508e56e
2 changed files with 28 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
drivers/gpio/gpiolib.c
View File

@ -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;
}

9
include/linux/gpio/driver.h
View File

@ -221,6 +221,15 @@ 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