From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001

From: Darren Kenny <darren.kenny@oracle.com>

Date: Wed, 4 Nov 2020 14:43:44 +0000

Subject: [PATCH] video/fb/video_fb: Fix multiple integer overflows

The calculation of the unsigned 64-bit value is being generated by

multiplying 2, signed or unsigned, 32-bit integers which may overflow

before promotion to unsigned 64-bit. Fix all of them.

Fixes: CID 73703, CID 73767, CID 73833

Signed-off-by: Darren Kenny <darren.kenny@oracle.com>

Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

---

 grub-core/video/fb/video_fb.c | 52 ++++++++++++++++++++++++++++++-------------

 1 file changed, 36 insertions(+), 16 deletions(-)

diff --git a/grub-core/video/fb/video_fb.c b/grub-core/video/fb/video_fb.c

index 1a602c8b251..1c9a138dcdc 100644

--- a/grub-core/video/fb/video_fb.c

+++ b/grub-core/video/fb/video_fb.c

@@ -25,6 +25,7 @@

 #include <grub/fbutil.h>

 #include <grub/bitmap.h>

 #include <grub/dl.h>

+#include <grub/safemath.h>

 GRUB_MOD_LICENSE ("GPLv3+");

@@ -1417,15 +1418,23 @@ doublebuf_blit_update_screen (void)

 {

   if (framebuffer.current_dirty.first_line

       <= framebuffer.current_dirty.last_line)

-    grub_memcpy ((char *) framebuffer.pages[0]

-		 + framebuffer.current_dirty.first_line

-		 * framebuffer.back_target->mode_info.pitch,

-		 (char *) framebuffer.back_target->data

-		 + framebuffer.current_dirty.first_line

-		 * framebuffer.back_target->mode_info.pitch,

-		 framebuffer.back_target->mode_info.pitch

-		 * (framebuffer.current_dirty.last_line

-		    - framebuffer.current_dirty.first_line));

+    {

+      grub_size_t copy_size;

+

+      if (grub_sub (framebuffer.current_dirty.last_line,

+		    framebuffer.current_dirty.first_line, &copy_size) ||

+	  grub_mul (framebuffer.back_target->mode_info.pitch, copy_size, &copy_size))

+	{

+	  /* Shouldn't happen, but if it does we've a bug. */

+	  return GRUB_ERR_BUG;

+	}

+

+      grub_memcpy ((char *) framebuffer.pages[0] + framebuffer.current_dirty.first_line *

+		   framebuffer.back_target->mode_info.pitch,

+		   (char *) framebuffer.back_target->data + framebuffer.current_dirty.first_line *

+		   framebuffer.back_target->mode_info.pitch,

+		   copy_size);

+    }

   framebuffer.current_dirty.first_line

     = framebuffer.back_target->mode_info.height;

   framebuffer.current_dirty.last_line = 0;

@@ -1439,7 +1448,7 @@ grub_video_fb_doublebuf_blit_init (struct grub_video_fbrender_target **back,

 				   volatile void *framebuf)

 {

   grub_err_t err;

-  grub_size_t page_size = mode_info.pitch * mode_info.height;

+  grub_size_t page_size = (grub_size_t) mode_info.pitch * mode_info.height;

   framebuffer.offscreen_buffer = grub_zalloc (page_size);

   if (! framebuffer.offscreen_buffer)

@@ -1482,12 +1491,23 @@ doublebuf_pageflipping_update_screen (void)

     last_line = framebuffer.previous_dirty.last_line;

   if (first_line <= last_line)

-    grub_memcpy ((char *) framebuffer.pages[framebuffer.render_page]

-		 + first_line * framebuffer.back_target->mode_info.pitch,

-		 (char *) framebuffer.back_target->data

-		 + first_line * framebuffer.back_target->mode_info.pitch,

-		 framebuffer.back_target->mode_info.pitch

-		 * (last_line - first_line));

+    {

+      grub_size_t copy_size;

+

+      if (grub_sub (last_line, first_line, &copy_size) ||

+	  grub_mul (framebuffer.back_target->mode_info.pitch, copy_size, &copy_size))

+	{

+	  /* Shouldn't happen, but if it does we've a bug. */

+	  return GRUB_ERR_BUG;

+	}

+

+      grub_memcpy ((char *) framebuffer.pages[framebuffer.render_page] + first_line *

+		   framebuffer.back_target->mode_info.pitch,

+		   (char *) framebuffer.back_target->data + first_line *

+		   framebuffer.back_target->mode_info.pitch,

+		   copy_size);

+    }

+

   framebuffer.previous_dirty = framebuffer.current_dirty;

   framebuffer.current_dirty.first_line

     = framebuffer.back_target->mode_info.height;