From ac7dbb991ee5afc0beacce3a252dcaaa249a7786 Mon Sep 17 00:00:00 2001 From: Lars-Peter Clausen Date: Tue, 18 Oct 2016 16:54:06 +0200 Subject: gpio: GPIO_GET_LINEEVENT_IOCTL: Reject invalid line and event flags The GPIO_GET_LINEEVENT_IOCTL currently ignores unknown or undefined linehandle and lineevent flags. From a backwards and forwards compatibility viewpoint it is highly desirable to reject unknown flags though. On one hand an application that is using newer flags and is running on an older kernel has no way to detect if the new flags were handled correctly if they are silently discarded. On the other hand an application that (accidentally) passes undefined flags will run fine on an older kernel, but may break on a newer kernel when these flags get defined. Ensure that requests that have undefined flags set are rejected with an error, rather than silently discarding the undefined flags. Cc: stable@vger.kernel.org Fixes: 61f922db7221 ("gpio: userspace ABI for reading GPIO line events") Signed-off-by: Lars-Peter Clausen Signed-off-by: Linus Walleij --- drivers/gpio/gpiolib.c | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'drivers/gpio') diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index b5b1a8425907..20e09b7c2de3 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -556,6 +556,10 @@ struct lineevent_state { struct mutex read_lock; }; +#define GPIOEVENT_REQUEST_VALID_FLAGS \ + (GPIOEVENT_REQUEST_RISING_EDGE | \ + GPIOEVENT_REQUEST_FALLING_EDGE) + static unsigned int lineevent_poll(struct file *filep, struct poll_table_struct *wait) { @@ -753,6 +757,13 @@ static int lineevent_create(struct gpio_device *gdev, void __user *ip) goto out_free_label; } + /* Return an error if a unknown flag is set */ + if ((lflags & ~GPIOHANDLE_REQUEST_VALID_FLAGS) || + (eflags & ~GPIOEVENT_REQUEST_VALID_FLAGS)) { + ret = -EINVAL; + goto out_free_label; + } + /* This is just wrong: we don't look for events on output lines */ if (lflags & GPIOHANDLE_REQUEST_OUTPUT) { ret = -EINVAL; -- cgit v1.2.3-59-g8ed1b