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Subject[PATCH 4.9 26/44] Input: uinput - fix undefined behavior in uinput_validate_absinfo()
Date
4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Dmitry Torokhov <dmitry.torokhov@gmail.com>

commit d77651a227f8920dd7ec179b84e400cce844eeb3 upstream.

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>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Cc: stable@vger.kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/input/misc/uinput.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

--- a/drivers/input/misc/uinput.c
+++ b/drivers/input/misc/uinput.c
@@ -39,6 +39,7 @@
#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <linux/uinput.h>
+#include <linux/overflow.h>
#include <linux/input/mt.h>
#include "../input-compat.h"

@@ -335,7 +336,7 @@ static int uinput_open(struct inode *ino
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;
@@ -347,7 +348,7 @@ static int uinput_validate_absinfo(struc
return -EINVAL;
}

- if (abs->flat > max - min) {
+ if (!check_sub_overflow(max, min, &range) && abs->flat > range) {
printk(KERN_DEBUG
"%s: abs_flat #%02x out of range: %d (min:%d/max:%d)\n",
UINPUT_NAME, code, abs->flat, min, max);

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