grub2/0418-video-fb-video_fb-Fix-possible-integer-overflow.patch

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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Darren Kenny <darren.kenny@oracle.com>
Date: Fri, 4 Dec 2020 14:51:30 +0000
Subject: [PATCH] video/fb/video_fb: Fix possible integer overflow
It is minimal possibility that the values being used here will overflow.
So, change the code to use the safemath function grub_mul() to ensure
that doesn't happen.
Fixes: CID 73761
Signed-off-by: Darren Kenny <darren.kenny@oracle.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
---
grub-core/video/fb/video_fb.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/grub-core/video/fb/video_fb.c b/grub-core/video/fb/video_fb.c
index 1c9a138dc..ae6b89f9a 100644
--- a/grub-core/video/fb/video_fb.c
+++ b/grub-core/video/fb/video_fb.c
@@ -1537,7 +1537,13 @@ doublebuf_pageflipping_init (struct grub_video_mode_info *mode_info,
volatile void *page1_ptr)
{
grub_err_t err;
- grub_size_t page_size = mode_info->pitch * mode_info->height;
+ grub_size_t page_size = 0;
+
+ if (grub_mul (mode_info->pitch, mode_info->height, &page_size))
+ {
+ /* Shouldn't happen, but if it does we've a bug. */
+ return GRUB_ERR_BUG;
+ }
framebuffer.offscreen_buffer = grub_malloc (page_size);
if (! framebuffer.offscreen_buffer)