RE: [PATCH 07/12] iommufd: Add IOMMU_HWPT_INVALIDATE

["Liu, Yi L" <yi.l.liu@intel.com>]

> From: Jason Gunthorpe <jgg@nvidia.com>
> Sent: Saturday, March 11, 2023 1:50 AM
> 
> On Thu, Mar 09, 2023 at 12:09:05AM -0800, Yi Liu wrote:
> > +int iommufd_hwpt_invalidate(struct iommufd_ucmd *ucmd)
> > +{
> > +	struct iommu_hwpt_invalidate *cmd = ucmd->cmd;
> > +	struct iommufd_hw_pagetable *hwpt;
> > +	u64 user_ptr;
> > +	u32 user_data_len, klen;
> > +	int rc = 0;
> > +
> > +	/*
> > +	 * For a user-managed HWPT, type should not be
> IOMMU_HWPT_TYPE_DEFAULT.
> > +	 * data_len should not exceed the size of
> iommufd_invalidate_buffer.
> > +	 */
> > +	if (cmd->data_type == IOMMU_HWPT_TYPE_DEFAULT || !cmd-
> >data_len ||
> > +	    cmd->data_type >=
> ARRAY_SIZE(iommufd_hwpt_invalidate_info_size))
> > +		return -EOPNOTSUPP;
> 
> This needs to do the standard check for zeros in unknown trailing data
> bit. Check that alloc does it too

Maybe it has been covered by the copy_struct_from_user(). Is it?

+	/*
+	 * Copy the needed fields before reusing the ucmd buffer, this
+	 * avoids memory allocation in this path.
+	 */
+	user_ptr = cmd->data_uptr;
+	user_data_len = cmd->data_len;
+
+	rc = copy_struct_from_user(cmd, klen,
+				   u64_to_user_ptr(user_ptr), user_data_len);

Regards,
Yi Liu