From e3e847c7f15a27c80f526b2a7a8d4dd7ce0960a0 Mon Sep 17 00:00:00 2001 From: Lars-Peter Clausen Date: Tue, 18 Oct 2016 16:54:05 +0200 Subject: [PATCH] gpio: GPIO_GET_LINEHANDLE_IOCTL: Reject invalid line flags The GPIO_GET_LINEHANDLE_IOCTL currently ignores unknown or undefined linehandle 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: d7c51b47ac11 ("gpio: userspace ABI for reading/writing GPIO lines") Signed-off-by: Lars-Peter Clausen Signed-off-by: Linus Walleij --- drivers/gpio/gpiolib.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index 7f92f8964efd..b5b1a8425907 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -333,6 +333,13 @@ struct linehandle_state { u32 numdescs; }; +#define GPIOHANDLE_REQUEST_VALID_FLAGS \ + (GPIOHANDLE_REQUEST_INPUT | \ + GPIOHANDLE_REQUEST_OUTPUT | \ + GPIOHANDLE_REQUEST_ACTIVE_LOW | \ + GPIOHANDLE_REQUEST_OPEN_DRAIN | \ + GPIOHANDLE_REQUEST_OPEN_SOURCE) + static long linehandle_ioctl(struct file *filep, unsigned int cmd, unsigned long arg) { @@ -451,6 +458,12 @@ static int linehandle_create(struct gpio_device *gdev, void __user *ip) goto out_free_descs; } + /* Return an error if a unknown flag is set */ + if (lflags & ~GPIOHANDLE_REQUEST_VALID_FLAGS) { + ret = -EINVAL; + goto out_free_descs; + } + desc = &gdev->descs[offset]; ret = gpiod_request(desc, lh->label); if (ret) -- 2.20.1