1 files changed, 21 insertions, 46 deletions

diff --git a/drivers/media/common/videobuf2/frame_vector.c b/drivers/media/common/videobuf2/frame_vector.c
index ce879f6f8f82..41f289c75cbb 100644
--- a/drivers/media/common/videobuf2/frame_vector.c
+++ b/drivers/media/common/videobuf2/frame_vector.c
@@ -14,6 +14,7 @@
  * get_vaddr_frames() - map virtual addresses to pfns
  * @start:	starting user address
  * @nr_frames:	number of pages / pfns from start to map
+ * @write:	the mapped address has write permission
  * @vec:	structure which receives pages / pfns of the addresses mapped.
  *		It should have space for at least nr_frames entries.
  *
@@ -30,15 +31,17 @@
  * different type underlying the specified range of virtual addresses.
  * When the function isn't able to map a single page, it returns error.
  *
+ * Note that get_vaddr_frames() cannot follow VM_IO mappings. It used
+ * to be able to do that, but that could (racily) return non-refcounted
+ * pfns.
+ *
  * This function takes care of grabbing mmap_lock as necessary.
  */
-int get_vaddr_frames(unsigned long start, unsigned int nr_frames,
+int get_vaddr_frames(unsigned long start, unsigned int nr_frames, bool write,
 		     struct frame_vector *vec)
 {
-	struct mm_struct *mm = current->mm;
-	struct vm_area_struct *vma;
-	int ret = 0;
-	int err;
+	int ret;
+	unsigned int gup_flags = FOLL_LONGTERM;
 
 	if (nr_frames == 0)
 		return 0;
@@ -48,48 +51,20 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames,
 
 	start = untagged_addr(start);
 
-	ret = pin_user_pages_fast(start, nr_frames,
-				  FOLL_FORCE | FOLL_WRITE | FOLL_LONGTERM,
+	if (write)
+		gup_flags |= FOLL_WRITE;
+
+	ret = pin_user_pages_fast(start, nr_frames, gup_flags,
 				  (struct page **)(vec->ptrs));
-	if (ret > 0) {
-		vec->got_ref = true;
-		vec->is_pfns = false;
-		goto out_unlocked;
-	}
+	vec->got_ref = true;
+	vec->is_pfns = false;
+	vec->nr_frames = ret;
 
-	mmap_read_lock(mm);
-	vec->got_ref = false;
-	vec->is_pfns = true;
-	ret = 0;
-	do {
-		unsigned long *nums = frame_vector_pfns(vec);
-
-		vma = vma_lookup(mm, start);
-		if (!vma)
-			break;
-
-		while (ret < nr_frames && start + PAGE_SIZE <= vma->vm_end) {
-			err = follow_pfn(vma, start, &nums[ret]);
-			if (err) {
-				if (ret == 0)
-					ret = err;
-				goto out;
-			}
-			start += PAGE_SIZE;
-			ret++;
-		}
-		/* Bail out if VMA doesn't completely cover the tail page. */
-		if (start < vma->vm_end)
-			break;
-	} while (ret < nr_frames);
-out:
-	mmap_read_unlock(mm);
-out_unlocked:
-	if (!ret)
-		ret = -EFAULT;
-	if (ret > 0)
-		vec->nr_frames = ret;
-	return ret;
+	if (likely(ret > 0))
+		return ret;
+
+	vec->nr_frames = 0;
+	return ret ? ret : -EFAULT;
 }
 EXPORT_SYMBOL(get_vaddr_frames);
 
@@ -184,7 +159,7 @@ EXPORT_SYMBOL(frame_vector_to_pfns);
 struct frame_vector *frame_vector_create(unsigned int nr_frames)
 {
 	struct frame_vector *vec;
-	int size = sizeof(struct frame_vector) + sizeof(void *) * nr_frames;
+	int size = struct_size(vec, ptrs, nr_frames);
 
 	if (WARN_ON_ONCE(nr_frames == 0))
 		return NULL;