IOMMU Fixes for Linux v4.4-rc5

* Two similar fixes for the Intel and AMD IOMMU drivers to add
 	  proper access checks before calling handle_mm_fault.
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Merge tag 'iommu-fixes-v4.4-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu

Pull IOMMU fixes from Joerg Roedel:
 "Two similar fixes for the Intel and AMD IOMMU drivers to add proper
  access checks before calling handle_mm_fault"

* tag 'iommu-fixes-v4.4-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu:
  iommu/vt-d: Do access checks before calling handle_mm_fault()
  iommu/amd: Do proper access checking before calling handle_mm_fault()

drivers/iommu/amd_iommu_v2.c

@@ -494,6 +494,22 @@ static void handle_fault_error(struct fault *fault)
 	}
 }
 
+static bool access_error(struct vm_area_struct *vma, struct fault *fault)
+{
+	unsigned long requested = 0;
+
+	if (fault->flags & PPR_FAULT_EXEC)
+		requested |= VM_EXEC;
+
+	if (fault->flags & PPR_FAULT_READ)
+		requested |= VM_READ;
+
+	if (fault->flags & PPR_FAULT_WRITE)
+		requested |= VM_WRITE;
+
+	return (requested & ~vma->vm_flags) != 0;
+}
+
 static void do_fault(struct work_struct *work)
 {
 	struct fault *fault = container_of(work, struct fault, work);
@@ -516,8 +532,8 @@ static void do_fault(struct work_struct *work)
 		goto out;
 	}
 
-	if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))) {
-		/* handle_mm_fault would BUG_ON() */
+	/* Check if we have the right permissions on the vma */
+	if (access_error(vma, fault)) {
 		up_read(&mm->mmap_sem);
 		handle_fault_error(fault);
 		goto out;

drivers/iommu/intel-svm.c

@@ -484,6 +484,23 @@ struct page_req_dsc {
 };
 
 #define PRQ_RING_MASK ((0x1000 << PRQ_ORDER) - 0x10)
+
+static bool access_error(struct vm_area_struct *vma, struct page_req_dsc *req)
+{
+	unsigned long requested = 0;
+
+	if (req->exe_req)
+		requested |= VM_EXEC;
+
+	if (req->rd_req)
+		requested |= VM_READ;
+
+	if (req->wr_req)
+		requested |= VM_WRITE;
+
+	return (requested & ~vma->vm_flags) != 0;
+}
+
 static irqreturn_t prq_event_thread(int irq, void *d)
 {
 	struct intel_iommu *iommu = d;
@@ -539,6 +556,9 @@ static irqreturn_t prq_event_thread(int irq, void *d)
 		if (!vma || address < vma->vm_start)
 			goto invalid;
 
+		if (access_error(vma, req))
+			goto invalid;
+
 		ret = handle_mm_fault(svm->mm, vma, address,
 				      req->wr_req ? FAULT_FLAG_WRITE : 0);
 		if (ret & VM_FAULT_ERROR)