vduse: fix memory corruption in vduse_dev_ioctl()

In the Linux kernel, the following vulnerability has been resolved: vduse: fix memory corruption in vduse_dev_ioctl() The "config.offset" comes from the user. There needs to a check to prevent it being out of bounds. The "config.offset" and "dev->config_size" variables are both type u32. So if the offset if out of bounds then the "dev->config_size - config.offset" subtraction results in a very high u32 value. The out of bounds offset can result in memory corruption.