Blame SOURCES/0417-video-fb-video_fb-Fix-multiple-integer-overflows.patch

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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Darren Kenny <darren.kenny@oracle.com>
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Date: Wed, 4 Nov 2020 14:43:44 +0000
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Subject: [PATCH] video/fb/video_fb: Fix multiple integer overflows
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The calculation of the unsigned 64-bit value is being generated by
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multiplying 2, signed or unsigned, 32-bit integers which may overflow
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before promotion to unsigned 64-bit. Fix all of them.
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Fixes: CID 73703, CID 73767, CID 73833
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Signed-off-by: Darren Kenny <darren.kenny@oracle.com>
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Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
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---
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 grub-core/video/fb/video_fb.c | 52 ++++++++++++++++++++++++++++++-------------
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 1 file changed, 36 insertions(+), 16 deletions(-)
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diff --git a/grub-core/video/fb/video_fb.c b/grub-core/video/fb/video_fb.c
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index 1a602c8b2..1c9a138dc 100644
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--- a/grub-core/video/fb/video_fb.c
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+++ b/grub-core/video/fb/video_fb.c
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@@ -25,6 +25,7 @@
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 #include <grub/fbutil.h>
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 #include <grub/bitmap.h>
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 #include <grub/dl.h>
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+#include <grub/safemath.h>
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 GRUB_MOD_LICENSE ("GPLv3+");
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@@ -1417,15 +1418,23 @@ doublebuf_blit_update_screen (void)
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 {
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   if (framebuffer.current_dirty.first_line
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       <= framebuffer.current_dirty.last_line)
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-    grub_memcpy ((char *) framebuffer.pages[0]
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-		 + framebuffer.current_dirty.first_line
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-		 * framebuffer.back_target->mode_info.pitch,
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-		 (char *) framebuffer.back_target->data
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-		 + framebuffer.current_dirty.first_line
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-		 * framebuffer.back_target->mode_info.pitch,
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-		 framebuffer.back_target->mode_info.pitch
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-		 * (framebuffer.current_dirty.last_line
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-		    - framebuffer.current_dirty.first_line));
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+    {
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+      grub_size_t copy_size;
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+
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+      if (grub_sub (framebuffer.current_dirty.last_line,
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+		    framebuffer.current_dirty.first_line, &copy_size) ||
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+	  grub_mul (framebuffer.back_target->mode_info.pitch, copy_size, &copy_size))
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+	{
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+	  /* Shouldn't happen, but if it does we've a bug. */
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+	  return GRUB_ERR_BUG;
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+	}
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+
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+      grub_memcpy ((char *) framebuffer.pages[0] + framebuffer.current_dirty.first_line *
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+		   framebuffer.back_target->mode_info.pitch,
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+		   (char *) framebuffer.back_target->data + framebuffer.current_dirty.first_line *
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+		   framebuffer.back_target->mode_info.pitch,
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+		   copy_size);
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+    }
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   framebuffer.current_dirty.first_line
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     = framebuffer.back_target->mode_info.height;
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   framebuffer.current_dirty.last_line = 0;
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@@ -1439,7 +1448,7 @@ grub_video_fb_doublebuf_blit_init (struct grub_video_fbrender_target **back,
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 				   volatile void *framebuf)
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 {
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   grub_err_t err;
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-  grub_size_t page_size = mode_info.pitch * mode_info.height;
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+  grub_size_t page_size = (grub_size_t) mode_info.pitch * mode_info.height;
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   framebuffer.offscreen_buffer = grub_zalloc (page_size);
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   if (! framebuffer.offscreen_buffer)
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@@ -1482,12 +1491,23 @@ doublebuf_pageflipping_update_screen (void)
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     last_line = framebuffer.previous_dirty.last_line;
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   if (first_line <= last_line)
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-    grub_memcpy ((char *) framebuffer.pages[framebuffer.render_page]
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-		 + first_line * framebuffer.back_target->mode_info.pitch,
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-		 (char *) framebuffer.back_target->data
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-		 + first_line * framebuffer.back_target->mode_info.pitch,
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-		 framebuffer.back_target->mode_info.pitch
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-		 * (last_line - first_line));
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+    {
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+      grub_size_t copy_size;
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+
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+      if (grub_sub (last_line, first_line, &copy_size) ||
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+	  grub_mul (framebuffer.back_target->mode_info.pitch, copy_size, &copy_size))
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+	{
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+	  /* Shouldn't happen, but if it does we've a bug. */
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+	  return GRUB_ERR_BUG;
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+	}
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+
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+      grub_memcpy ((char *) framebuffer.pages[framebuffer.render_page] + first_line *
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+		   framebuffer.back_target->mode_info.pitch,
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+		   (char *) framebuffer.back_target->data + first_line *
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+		   framebuffer.back_target->mode_info.pitch,
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+		   copy_size);
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+    }
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+
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   framebuffer.previous_dirty = framebuffer.current_dirty;
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   framebuffer.current_dirty.first_line
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     = framebuffer.back_target->mode_info.height;