[PATCH v3 1/8] gpio: mockup: improve the debugfs input sanitization

Bartosz Golaszewski
2017-06-09T11:46:11Z

We're currently only checking the first character of the input to the
debugfs event files, so a string like '0sdfdsf' is valid and indicates
a falling edge event.

Be more strict and only allow '0', '1', '0\n' & '1\n'.

While we're at it: move the sanitization code before the irq_enabled
check so that we indicate an error on invalid input even if nobody is
waiting for events.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
---
drivers/gpio/gpio-mockup.c | 19 +++++++------------
1 file changed, 7 insertions(+), 12 deletions(-)

diff --git a/drivers/gpio/gpio-mockup.c b/drivers/gpio/gpio-mockup.c
index ba8d62a..da76267 100644
--- a/drivers/gpio/gpio-mockup.c
+++ b/drivers/gpio/gpio-mockup.c
@@ -208,8 +208,7 @@ static ssize_t gpio_mockup_event_write(struct file *file,
struct seq_file *sfile;
struct gpio_desc *desc;
struct gpio_chip *gc;
- int val;
- char buf;
+ int rv, val;

sfile = file->private_data;
priv = sfile->private;
@@ -217,19 +216,15 @@ static ssize_t gpio_mockup_event_write(struct file *file,
chip = priv->chip;
gc = &chip->gc;

+ rv = kstrtoint_from_user(usr_buf, size, 0, &val);
+ if (rv)
+ return rv;
+ if (val != 0 && val != 1)
+ return -EINVAL;
+
if (!chip->lines[priv->offset].irq_enabled)
return size;

- if (copy_from_user(&buf, usr_buf, 1))
- return -EFAULT;
-
- if (buf == '0')
- val = 0;
- else if (buf == '1')
- val = 1;
- else
- return -EINVAL;
-
gpiod_set_value_cansleep(desc, val);
priv->chip->irq_ctx.irq = gc->irq_base + priv->offset;
irq_work_queue(&priv->chip->irq_ctx.work);
--
2.9.3