[Lucid][CVE-2013-6763][PATCH 2/2] Fix a few incorrectly checked [io_]remap_pfn_range() calls

[Luis Henriques]

From: Linus Torvalds <torvalds at linux-foundation.org>

CVE-2013-6763

BugLink: http://bugs.launchpad.net/bugs/1252426

Nico Golde reports a few straggling uses of [io_]remap_pfn_range() that
really should use the vm_iomap_memory() helper.  This trivially converts
two of them to the helper, and comments about why the third one really
needs to continue to use remap_pfn_range(), and adds the missing size
check.

Reported-by: Nico Golde <nico at ngolde.de>
Cc: stable at kernel.org
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org.
(back ported from commit 7314e613d5ff9f0934f7a0f74ed7973b903315d1)
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/uio/uio.c        | 16 +++++++++++++++-
 drivers/video/au1100fb.c | 26 +-------------------------
 drivers/video/au1200fb.c | 23 +----------------------
 3 files changed, 17 insertions(+), 48 deletions(-)

diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
index e941367..e3804d3 100644
--- a/drivers/uio/uio.c
+++ b/drivers/uio/uio.c
@@ -669,16 +669,30 @@ static int uio_mmap_physical(struct vm_area_struct *vma)
 {
 	struct uio_device *idev = vma->vm_private_data;
 	int mi = uio_find_mem_index(vma);
+	struct uio_mem *mem;
 	if (mi < 0)
 		return -EINVAL;
+	mem = idev->info->mem + mi;
+
+	if (vma->vm_end - vma->vm_start > mem->size)
+		return -EINVAL;
 
 	vma->vm_flags |= VM_IO | VM_RESERVED;
 
 	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
 
+	/*
+	 * We cannot use the vm_iomap_memory() helper here,
+	 * because vma->vm_pgoff is the map index we looked
+	 * up above in uio_find_mem_index(), rather than an
+	 * actual page offset into the mmap.
+	 *
+	 * So we just do the physical mmap without a page
+	 * offset.
+	 */
 	return remap_pfn_range(vma,
 			       vma->vm_start,
-			       idev->info->mem[mi].addr >> PAGE_SHIFT,
+			       mem->addr >> PAGE_SHIFT,
 			       vma->vm_end - vma->vm_start,
 			       vma->vm_page_prot);
 }
diff --git a/drivers/video/au1100fb.c b/drivers/video/au1100fb.c
index a699aab..745e5b3 100644
--- a/drivers/video/au1100fb.c
+++ b/drivers/video/au1100fb.c
@@ -392,39 +392,15 @@ void au1100fb_fb_rotate(struct fb_info *fbi, int angle)
 int au1100fb_fb_mmap(struct fb_info *fbi, struct vm_area_struct *vma)
 {
 	struct au1100fb_device *fbdev;
-	unsigned int len;
-	unsigned long start=0, off;
 
 	fbdev = to_au1100fb_device(fbi);
 
-	if (vma->vm_pgoff > (~0UL >> PAGE_SHIFT)) {
-		return -EINVAL;
-	}
-
-	start = fbdev->fb_phys & PAGE_MASK;
-	len = PAGE_ALIGN((start & ~PAGE_MASK) + fbdev->fb_len);
-
-	off = vma->vm_pgoff << PAGE_SHIFT;
-
-	if ((vma->vm_end - vma->vm_start + off) > len) {
-		return -EINVAL;
-	}
-
-	off += start;
-	vma->vm_pgoff = off >> PAGE_SHIFT;
-
 	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
 	pgprot_val(vma->vm_page_prot) |= (6 << 9); //CCA=6
 
 	vma->vm_flags |= VM_IO;
 
-	if (io_remap_pfn_range(vma, vma->vm_start, off >> PAGE_SHIFT,
-				vma->vm_end - vma->vm_start,
-				vma->vm_page_prot)) {
-		return -EAGAIN;
-	}
-
-	return 0;
+	return vm_iomap_memory(vma, fbdev->fb_phys, fbdev->fb_len);
 }
 
 /* fb_cursor
diff --git a/drivers/video/au1200fb.c b/drivers/video/au1200fb.c
index 0d96f1d..8921b45 100644
--- a/drivers/video/au1200fb.c
+++ b/drivers/video/au1200fb.c
@@ -1241,40 +1241,19 @@ static int au1200fb_fb_blank(int blank_mode, struct fb_info *fbi)
  * method mainly to allow the use of the TLB streaming flag (CCA=6)
  */
 static int au1200fb_fb_mmap(struct fb_info *info, struct vm_area_struct *vma)
-
 {
-	unsigned int len;
-	unsigned long start=0, off;
 	struct au1200fb_device *fbdev = (struct au1200fb_device *) info;
 
 #ifdef CONFIG_PM
 	au1xxx_pm_access(LCD_pm_dev);
 #endif
 
-	if (vma->vm_pgoff > (~0UL >> PAGE_SHIFT)) {
-		return -EINVAL;
-	}
-
-	start = fbdev->fb_phys & PAGE_MASK;
-	len = PAGE_ALIGN((start & ~PAGE_MASK) + fbdev->fb_len);
-
-	off = vma->vm_pgoff << PAGE_SHIFT;
-
-	if ((vma->vm_end - vma->vm_start + off) > len) {
-		return -EINVAL;
-	}
-
-	off += start;
-	vma->vm_pgoff = off >> PAGE_SHIFT;
-
 	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
 	pgprot_val(vma->vm_page_prot) |= _CACHE_MASK; /* CCA=7 */
 
 	vma->vm_flags |= VM_IO;
 
-	return io_remap_pfn_range(vma, vma->vm_start, off >> PAGE_SHIFT,
-				  vma->vm_end - vma->vm_start,
-				  vma->vm_page_prot);
+	return vm_iomap_memory(vma, fbdev->fb_phys, fbdev->fb_len);
 
 	return 0;
 }
-- 
1.8.3.2