From 23843fe8947e4da955a05ad3d1858725bfcb56c8 Mon Sep 17 00:00:00 2001

From: Zhang Boyang <zhangboyang.id@gmail.com>

Date: Fri, 5 Aug 2022 02:27:05 +0800

Subject: [PATCH 04/12] font: Fix integer overflow in ensure_comb_space()

In fact it can't overflow at all because glyph_id->ncomb is only 8-bit

wide. But let's keep safe if somebody changes the width of glyph_id->ncomb

in the future. This patch also fixes the inconsistency between

render_max_comb_glyphs and render_combining_glyphs when grub_malloc()

returns NULL.

Signed-off-by: Zhang Boyang <zhangboyang.id@gmail.com>

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

---

 grub-core/font/font.c | 14 +++++++++-----

 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/grub-core/font/font.c b/grub-core/font/font.c

index a8576ffec..9e3e0a94e 100644

--- a/grub-core/font/font.c

+++ b/grub-core/font/font.c

@@ -1468,14 +1468,18 @@ ensure_comb_space (const struct grub_unicode_glyph *glyph_id)

   if (glyph_id->ncomb <= render_max_comb_glyphs)

     return;

-  render_max_comb_glyphs = 2 * glyph_id->ncomb;

-  if (render_max_comb_glyphs < 8)

+  if (grub_mul (glyph_id->ncomb, 2, &render_max_comb_glyphs))

+    render_max_comb_glyphs = 0;

+  if (render_max_comb_glyphs > 0 && render_max_comb_glyphs < 8)

     render_max_comb_glyphs = 8;

   grub_free (render_combining_glyphs);

-  render_combining_glyphs = grub_malloc (render_max_comb_glyphs

-					 * sizeof (render_combining_glyphs[0]));

+  render_combining_glyphs = (render_max_comb_glyphs > 0) ?

+    grub_calloc (render_max_comb_glyphs, sizeof (render_combining_glyphs[0])) : NULL;

   if (!render_combining_glyphs)

-    grub_errno = 0;

+    {

+      render_max_comb_glyphs = 0;

+      grub_errno = GRUB_ERR_NONE;

+    }

 }

 int

-- 

2.33.5