proxmox-mirrors/grub2
1
0
Fork 0
mirror of https://git.proxmox.com/git/grub2 synced 2025-08-15 08:40:35 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

font: Fix integer overflow in BMP index

Browse Source 
The BMP index (font->bmp_idx) is designed as a reverse lookup table of
char entries (font->char_index), in order to speed up lookups for BMP
chars (i.e. code < 0x10000). The values in BMP index are the subscripts
of the corresponding char entries, stored in grub_uint16_t, while 0xffff
means not found.

This patch fixes the problem of large subscript truncated to grub_uint16_t,
leading BMP index to return wrong char entry or report false miss. The
code now checks for bounds and uses BMP index as a hint, and fallbacks
to binary-search if necessary.

On the occasion add a comment about BMP index is initialized to 0xffff.

Signed-off-by: Zhang Boyang <zhangboyang.id@gmail.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
This commit is contained in:
Zhang Boyang 2022-08-15 02:04:58 +08:00 committed by Steve McIntyre
parent 96409d679a
commit b24a98f935
2 changed files with 74 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

65
debian/patches/cve_2022_2601/0007-font-Fix-integer-overflow-in-BMP-index.patch vendored Normal file
View File

@ -0,0 +1,65 @@
From afda8b60ba0712abe01ae1e64c5f7a067a0e6492 Mon Sep 17 00:00:00 2001
From: Zhang Boyang <zhangboyang.id@gmail.com>
Date: Mon, 15 Aug 2022 02:04:58 +0800
Subject: [PATCH 07/14] font: Fix integer overflow in BMP index
The BMP index (font->bmp_idx) is designed as a reverse lookup table of
char entries (font->char_index), in order to speed up lookups for BMP
chars (i.e. code < 0x10000). The values in BMP index are the subscripts
of the corresponding char entries, stored in grub_uint16_t, while 0xffff
means not found.
This patch fixes the problem of large subscript truncated to grub_uint16_t,
leading BMP index to return wrong char entry or report false miss. The
code now checks for bounds and uses BMP index as a hint, and fallbacks
to binary-search if necessary.
On the occasion add a comment about BMP index is initialized to 0xffff.
Signed-off-by: Zhang Boyang <zhangboyang.id@gmail.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
---
grub-core/font/font.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/grub-core/font/font.c b/grub-core/font/font.c
index 9e3e0a94e..e4cb0d867 100644
--- a/grub-core/font/font.c
+++ b/grub-core/font/font.c
@@ -300,6 +300,8 @@ load_font_index (grub_file_t file, grub_uint32_t sect_length, struct
font->bmp_idx = grub_malloc (0x10000 * sizeof (grub_uint16_t));
if (!font->bmp_idx)
return 1;
+
+ /* Init the BMP index array to 0xffff. */
grub_memset (font->bmp_idx, 0xff, 0x10000 * sizeof (grub_uint16_t));
@@ -328,7 +330,7 @@ load_font_index (grub_file_t file, grub_uint32_t sect_length, struct
return 1;
}
- if (entry->code < 0x10000)
+ if (entry->code < 0x10000 && i < 0xffff)
font->bmp_idx[entry->code] = i;
last_code = entry->code;
@@ -696,9 +698,12 @@ find_glyph (const grub_font_t font, grub_uint32_t code)
/* Use BMP index if possible. */
if (code < 0x10000 && font->bmp_idx)
{
- if (font->bmp_idx[code] == 0xffff)
- return 0;
- return &table[font->bmp_idx[code]];
+ if (font->bmp_idx[code] < 0xffff)
+ return &table[font->bmp_idx[code]];
+ /*
+ * When we are here then lookup in BMP index result in miss,
+ * fallthough to binary-search.
+ */
}
/* Do a binary search in `char_index', which is ordered by code point. */
--
2.30.2

11
grub-core/font/font.c
View File

@ -300,6 +300,8 @@ load_font_index (grub_file_t file, grub_uint32_t sect_length, struct
font->bmp_idx = grub_malloc (0x10000 * sizeof (grub_uint16_t));
if (!font->bmp_idx)
return 1;
/* Init the BMP index array to 0xffff. */
grub_memset (font->bmp_idx, 0xff, 0x10000 * sizeof (grub_uint16_t));
@ -328,7 +330,7 @@ load_font_index (grub_file_t file, grub_uint32_t sect_length, struct
return 1;
}
if (entry->code < 0x10000)
if (entry->code < 0x10000 && i < 0xffff)
font->bmp_idx[entry->code] = i;
last_code = entry->code;
@ -696,9 +698,12 @@ find_glyph (const grub_font_t font, grub_uint32_t code)
/* Use BMP index if possible. */
if (code < 0x10000 && font->bmp_idx)
{
if (font->bmp_idx[code] == 0xffff)
return 0;
if (font->bmp_idx[code] < 0xffff)
return &table[font->bmp_idx[code]];
/*
* When we are here then lookup in BMP index result in miss,
* fallthough to binary-search.
*/
}
/* Do a binary search in `char_index', which is ordered by code point. */