[PATCH 2/3] iommufd: Add check on user response code

[Lu Baolu <baolu.lu@linux.intel.com>]

The response code from user space is only allowed to be SUCCESS or
INVALID. All other values are treated by the device as a response
code of Response Failure according to PCI spec, section 10.4.2.1.
This response disables the Page Request Interface for the Function.

Add a check in iommufd_fault_fops_write() to avoid invalid response
code.

Fixes: 07838f7fd529 ("iommufd: Add iommufd fault object")
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
 drivers/iommu/iommufd/fault.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/iommu/iommufd/fault.c b/drivers/iommu/iommufd/fault.c
index 54d6cd20a673..044b9b97da31 100644
--- a/drivers/iommu/iommufd/fault.c
+++ b/drivers/iommu/iommufd/fault.c
@@ -305,6 +305,12 @@ static ssize_t iommufd_fault_fops_write(struct file *filep, const char __user *b
 		if (rc)
 			break;
 
+		if (response.code != IOMMUFD_PAGE_RESP_SUCCESS &&
+		    response.code != IOMMUFD_PAGE_RESP_INVALID) {
+			rc = -EINVAL;
+			break;
+		}
+
 		group = xa_erase(&fault->response, response.cookie);
 		if (!group) {
 			rc = -EINVAL;
-- 
2.34.1