i2c: dev: copy userspace array safely

i2c-dev.c utilizes memdup_user() to copy a userspace array. This is done
without an overflow check.

Use the new wrapper memdup_array_user() to copy the array more safely.
Suggested-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Philipp Stanner <pstanner@redhat.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

drivers/i2c/i2c-dev.c

@@ -450,8 +450,8 @@ static long i2cdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 		if (rdwr_arg.nmsgs > I2C_RDWR_IOCTL_MAX_MSGS)
 			return -EINVAL;
 
-		rdwr_pa = memdup_user(rdwr_arg.msgs,
-				      rdwr_arg.nmsgs * sizeof(struct i2c_msg));
+		rdwr_pa = memdup_array_user(rdwr_arg.msgs,
+					    rdwr_arg.nmsgs, sizeof(struct i2c_msg));
 		if (IS_ERR(rdwr_pa))
 			return PTR_ERR(rdwr_pa);