Re: [PATCH v1 7/8] vfio/type1: Add VFIO_IOMMU_CACHE_INVALIDATE

Christoph Hellwig
2020-03-31T07:56:10Z

> @@ -2629,6 +2638,46 @@ static long vfio_iommu_type1_ioctl(void *iommu_data,
> }
> kfree(gbind_data);
> return ret;
> + } else if (cmd == VFIO_IOMMU_CACHE_INVALIDATE) {

Please refactor the spaghetti in this ioctl handler to use a switch
statement and a helper function per command before growing it even more.

> + /* Get the version of struct iommu_cache_invalidate_info */
> + if (copy_from_user(&version,
> + (void __user *) (arg + minsz), sizeof(version)))
> + return -EFAULT;
> +
> + info_size = iommu_uapi_get_data_size(
> + IOMMU_UAPI_CACHE_INVAL, version);
> +
> + cache_info = kzalloc(info_size, GFP_KERNEL);
> + if (!cache_info)
> + return -ENOMEM;
> +
> + if (copy_from_user(cache_info,
> + (void __user *) (arg + minsz), info_size)) {

The user might have changed the version while you were allocating and
freeing the memory, introducing potentially exploitable racing
conditions.