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SubjectRe: [PATCH] Input: uinput - fix undefined behavior in uinput_validate_absinfo()
On Mon, Jan 14, 2019 at 02:04:48PM -0800, Dmitry Torokhov wrote:
> An integer overflow may arise in uinput_validate_absinfo() if "max - min"
> can't be represented by an "int". We should check for overflow before
> trying to use the result.
>
> Reported-by: Kyungtae Kim <kt0755@gmail.com>
> Cc: stable@vger.kernel.org
> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
> ---
> drivers/input/misc/uinput.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/input/misc/uinput.c b/drivers/input/misc/uinput.c
> index 8ec483e8688b..26ec603fe220 100644
> --- a/drivers/input/misc/uinput.c
> +++ b/drivers/input/misc/uinput.c
> @@ -39,6 +39,7 @@
> #include <linux/init.h>
> #include <linux/fs.h>
> #include <linux/miscdevice.h>
> +#include <linux/overflow.h>
> #include <linux/input/mt.h>
> #include "../input-compat.h"
>
> @@ -405,7 +406,7 @@ static int uinput_open(struct inode *inode, struct file *file)
> static int uinput_validate_absinfo(struct input_dev *dev, unsigned int code,
> const struct input_absinfo *abs)
> {
> - int min, max;
> + int min, max, range;
>
> min = abs->minimum;
> max = abs->maximum;
> @@ -417,7 +418,7 @@ static int uinput_validate_absinfo(struct input_dev *dev, unsigned int code,
> return -EINVAL;
> }
>
> - if (abs->flat > max - min) {
> + if (check_sub_overflow(max, min, &range) && abs->flat > range) {

This should be !check_sub_overflow(...) of course.

> printk(KERN_DEBUG
> "%s: abs_flat #%02x out of range: %d (min:%d/max:%d)\n",
> UINPUT_NAME, code, abs->flat, min, max);
> --
> 2.20.1.97.g81188d93c3-goog
>
>
> --
> Dmitry

--
Dmitry

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