4.18-stable review patch. If anyone has any objections, please let me know.
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From: Bartosz Golaszewski brgl@bgdev.pl
[ Upstream commit e5332d5437764f775cf4e3b8ca3bf592af063a02 ]
User space can currently both read and set values of input lines using the character device. This was not allowed by the old sysfs interface nor is it a correct behavior.
Check the first descriptor in the set for the OUT flag when asked to set values and return -EPERM if the line is input.
Signed-off-by: Bartosz Golaszewski brgl@bgdev.pl Signed-off-by: Linus Walleij linus.walleij@linaro.org Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/gpio/gpiolib.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)
--- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -449,7 +449,13 @@ static long linehandle_ioctl(struct file
return 0; } else if (cmd == GPIOHANDLE_SET_LINE_VALUES_IOCTL) { - /* TODO: check if descriptors are really output */ + /* + * All line descriptors were created at once with the same + * flags so just check if the first one is really output. + */ + if (!test_bit(FLAG_IS_OUT, &lh->descs[0]->flags)) + return -EPERM; + if (copy_from_user(&ghd, ip, sizeof(ghd))) return -EFAULT;