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Font CVE fixes

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Resolves: CVE-2022-2601
Signed-off-by: Robbie Harwood <rharwood@redhat.com>
This commit is contained in:
Robbie Harwood 2022-11-03 19:34:00 +00:00
parent 525d9dc867
commit f2a26f5bbb
15 changed files with 867 additions and 1 deletions
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32
0294-font-Reject-glyphs-exceeds-font-max_glyph_width-or-f.patch Normal file
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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Zhang Boyang <zhangboyang.id@gmail.com>
Date: Wed, 3 Aug 2022 19:45:33 +0800
Subject: [PATCH] font: Reject glyphs exceeds font->max_glyph_width or
font->max_glyph_height
Check glyph's width and height against limits specified in font's
metadata. Reject the glyph (and font) if such limits are exceeded.
Signed-off-by: Zhang Boyang <zhangboyang.id@gmail.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
(cherry picked from commit 5760fcfd466cc757540ea0d591bad6a08caeaa16)
(cherry picked from commit 3b410ef4bb95e607cadeba2193fa90ae9bddb98d)
---
grub-core/font/font.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/grub-core/font/font.c b/grub-core/font/font.c
index d09bb38d89..2f09a4a55b 100644
--- a/grub-core/font/font.c
+++ b/grub-core/font/font.c
@@ -760,7 +760,9 @@ grub_font_get_glyph_internal (grub_font_t font, grub_uint32_t code)
|| read_be_uint16 (font->file, &height) != 0
|| read_be_int16 (font->file, &xoff) != 0
|| read_be_int16 (font->file, &yoff) != 0
- || read_be_int16 (font->file, &dwidth) != 0)
+ || read_be_int16 (font->file, &dwidth) != 0
+ || width > font->max_char_width
+ || height > font->max_char_height)
{
remove_font (font);
return 0;

111
0295-font-Fix-size-overflow-in-grub_font_get_glyph_intern.patch Normal file
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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Zhang Boyang <zhangboyang.id@gmail.com>
Date: Fri, 5 Aug 2022 00:51:20 +0800
Subject: [PATCH] font: Fix size overflow in grub_font_get_glyph_internal()
The length of memory allocation and file read may overflow. This patch
fixes the problem by using safemath macros.
There is a lot of code repetition like "(x * y + 7) / 8". It is unsafe
if overflow happens. This patch introduces grub_video_bitmap_calc_1bpp_bufsz().
It is safe replacement for such code. It has safemath-like prototype.
This patch also introduces grub_cast(value, pointer), it casts value to
typeof(*pointer) then store the value to *pointer. It returns true when
overflow occurs or false if there is no overflow. The semantics of arguments
and return value are designed to be consistent with other safemath macros.
Signed-off-by: Zhang Boyang <zhangboyang.id@gmail.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
(cherry picked from commit 941d10ad6f1dcbd12fb613002249e29ba035f985)
(cherry picked from commit 6bca9693878bdf61dd62b8c784862a48e75f569a)
---
grub-core/font/font.c | 17 +++++++++++++----
include/grub/bitmap.h | 18 ++++++++++++++++++
include/grub/safemath.h | 2 ++
3 files changed, 33 insertions(+), 4 deletions(-)
diff --git a/grub-core/font/font.c b/grub-core/font/font.c
index 2f09a4a55b..6a3fbebbd8 100644
--- a/grub-core/font/font.c
+++ b/grub-core/font/font.c
@@ -739,7 +739,8 @@ grub_font_get_glyph_internal (grub_font_t font, grub_uint32_t code)
grub_int16_t xoff;
grub_int16_t yoff;
grub_int16_t dwidth;
- int len;
+ grub_ssize_t len;
+ grub_size_t sz;
if (index_entry->glyph)
/* Return cached glyph. */
@@ -768,9 +769,17 @@ grub_font_get_glyph_internal (grub_font_t font, grub_uint32_t code)
return 0;
}
- len = (width * height + 7) / 8;
- glyph = grub_malloc (sizeof (struct grub_font_glyph) + len);
- if (!glyph)
+ /* Calculate real struct size of current glyph. */
+ if (grub_video_bitmap_calc_1bpp_bufsz (width, height, &len) ||
+ grub_add (sizeof (struct grub_font_glyph), len, &sz))
+ {
+ remove_font (font);
+ return 0;
+ }
+
+ /* Allocate and initialize the glyph struct. */
+ glyph = grub_malloc (sz);
+ if (glyph == NULL)
{
remove_font (font);
return 0;
diff --git a/include/grub/bitmap.h b/include/grub/bitmap.h
index 5728f8ca3a..0d9603f619 100644
--- a/include/grub/bitmap.h
+++ b/include/grub/bitmap.h
@@ -23,6 +23,7 @@
#include <grub/symbol.h>
#include <grub/types.h>
#include <grub/video.h>
+#include <grub/safemath.h>
struct grub_video_bitmap
{
@@ -79,6 +80,23 @@ grub_video_bitmap_get_height (struct grub_video_bitmap *bitmap)
return bitmap->mode_info.height;
}
+/*
+ * Calculate and store the size of data buffer of 1bit bitmap in result.
+ * Equivalent to "*result = (width * height + 7) / 8" if no overflow occurs.
+ * Return true when overflow occurs or false if there is no overflow.
+ * This function is intentionally implemented as a macro instead of
+ * an inline function. Although a bit awkward, it preserves data types for
+ * safemath macros and reduces macro side effects as much as possible.
+ *
+ * XXX: Will report false overflow if width * height > UINT64_MAX.
+ */
+#define grub_video_bitmap_calc_1bpp_bufsz(width, height, result) \
+({ \
+ grub_uint64_t _bitmap_pixels; \
+ grub_mul ((width), (height), &_bitmap_pixels) ? 1 : \
+ grub_cast (_bitmap_pixels / GRUB_CHAR_BIT + !!(_bitmap_pixels % GRUB_CHAR_BIT), (result)); \
+})
+
void EXPORT_FUNC (grub_video_bitmap_get_mode_info) (struct grub_video_bitmap *bitmap,
struct grub_video_mode_info *mode_info);
diff --git a/include/grub/safemath.h b/include/grub/safemath.h
index c17b89bba1..bb0f826de1 100644
--- a/include/grub/safemath.h
+++ b/include/grub/safemath.h
@@ -30,6 +30,8 @@
#define grub_sub(a, b, res) __builtin_sub_overflow(a, b, res)
#define grub_mul(a, b, res) __builtin_mul_overflow(a, b, res)
+#define grub_cast(a, res) grub_add ((a), 0, (res))
+
#else
#error gcc 5.1 or newer or clang 3.8 or newer is required
#endif

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0296-font-Fix-several-integer-overflows-in-grub_font_cons.patch Normal file
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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Zhang Boyang <zhangboyang.id@gmail.com>
Date: Fri, 5 Aug 2022 01:58:27 +0800
Subject: [PATCH] font: Fix several integer overflows in
grub_font_construct_glyph()
This patch fixes several integer overflows in grub_font_construct_glyph().
Glyphs of invalid size, zero or leading to an overflow, are rejected.
The inconsistency between "glyph" and "max_glyph_size" when grub_malloc()
returns NULL is fixed too.
Fixes: CVE-2022-2601
Reported-by: Zhang Boyang <zhangboyang.id@gmail.com>
Signed-off-by: Zhang Boyang <zhangboyang.id@gmail.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
(cherry picked from commit b1805f251b31a9d3cfae5c3572ddfa630145dbbf)
(cherry picked from commit b91eb9bd6c724339b7d7bb4765b9d36f1ee88b84)
---
grub-core/font/font.c | 29 +++++++++++++++++------------
1 file changed, 17 insertions(+), 12 deletions(-)
diff --git a/grub-core/font/font.c b/grub-core/font/font.c
index 6a3fbebbd8..1fa181d4ca 100644
--- a/grub-core/font/font.c
+++ b/grub-core/font/font.c
@@ -1517,6 +1517,7 @@ grub_font_construct_glyph (grub_font_t hinted_font,
struct grub_video_signed_rect bounds;
static struct grub_font_glyph *glyph = 0;
static grub_size_t max_glyph_size = 0;
+ grub_size_t cur_glyph_size;
ensure_comb_space (glyph_id);
@@ -1533,29 +1534,33 @@ grub_font_construct_glyph (grub_font_t hinted_font,
if (!glyph_id->ncomb && !glyph_id->attributes)
return main_glyph;
- if (max_glyph_size < sizeof (*glyph) + (bounds.width * bounds.height + GRUB_CHAR_BIT - 1) / GRUB_CHAR_BIT)
+ if (grub_video_bitmap_calc_1bpp_bufsz (bounds.width, bounds.height, &cur_glyph_size) ||
+ grub_add (sizeof (*glyph), cur_glyph_size, &cur_glyph_size))
+ return main_glyph;
+
+ if (max_glyph_size < cur_glyph_size)
{
grub_free (glyph);
- max_glyph_size = (sizeof (*glyph) + (bounds.width * bounds.height + GRUB_CHAR_BIT - 1) / GRUB_CHAR_BIT) * 2;
- if (max_glyph_size < 8)
- max_glyph_size = 8;
- glyph = grub_malloc (max_glyph_size);
+ if (grub_mul (cur_glyph_size, 2, &max_glyph_size))
+ max_glyph_size = 0;
+ glyph = max_glyph_size > 0 ? grub_malloc (max_glyph_size) : NULL;
}
if (!glyph)
{
+ max_glyph_size = 0;
grub_errno = GRUB_ERR_NONE;
return main_glyph;
}
- grub_memset (glyph, 0, sizeof (*glyph)
- + (bounds.width * bounds.height
- + GRUB_CHAR_BIT - 1) / GRUB_CHAR_BIT);
+ grub_memset (glyph, 0, cur_glyph_size);
glyph->font = main_glyph->font;
- glyph->width = bounds.width;
- glyph->height = bounds.height;
- glyph->offset_x = bounds.x;
- glyph->offset_y = bounds.y;
+ if (bounds.width == 0 || bounds.height == 0 ||
+ grub_cast (bounds.width, &glyph->width) ||
+ grub_cast (bounds.height, &glyph->height) ||
+ grub_cast (bounds.x, &glyph->offset_x) ||
+ grub_cast (bounds.y, &glyph->offset_y))
+ return main_glyph;
if (glyph_id->attributes & GRUB_UNICODE_GLYPH_ATTRIBUTE_MIRROR)
grub_font_blit_glyph_mirror (glyph, main_glyph,

41
0297-font-Remove-grub_font_dup_glyph.patch Normal file
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@ -0,0 +1,41 @@
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Zhang Boyang <zhangboyang.id@gmail.com>
Date: Fri, 5 Aug 2022 02:13:29 +0800
Subject: [PATCH] font: Remove grub_font_dup_glyph()
Remove grub_font_dup_glyph() since nobody is using it since 2013, and
I'm too lazy to fix the integer overflow problem in it.
Signed-off-by: Zhang Boyang <zhangboyang.id@gmail.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
(cherry picked from commit 25ad31c19c331aaa2dbd9bd2b2e2655de5766a9d)
(cherry picked from commit ad950e1e033318bb50222ed268a6dcfb97389035)
---
grub-core/font/font.c | 14 --------------
1 file changed, 14 deletions(-)
diff --git a/grub-core/font/font.c b/grub-core/font/font.c
index 1fa181d4ca..a115a63b0c 100644
--- a/grub-core/font/font.c
+++ b/grub-core/font/font.c
@@ -1055,20 +1055,6 @@ grub_font_get_glyph_with_fallback (grub_font_t font, grub_uint32_t code)
return best_glyph;
}
-#if 0
-static struct grub_font_glyph *
-grub_font_dup_glyph (struct grub_font_glyph *glyph)
-{
- static struct grub_font_glyph *ret;
- ret = grub_malloc (sizeof (*ret) + (glyph->width * glyph->height + 7) / 8);
- if (!ret)
- return NULL;
- grub_memcpy (ret, glyph, sizeof (*ret)
- + (glyph->width * glyph->height + 7) / 8);
- return ret;
-}
-#endif
-
/* FIXME: suboptimal. */
static void
grub_font_blit_glyph (struct grub_font_glyph *target,

47
0298-font-Fix-integer-overflow-in-ensure_comb_space.patch Normal file
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@ -0,0 +1,47 @@
From 0000000000000000000000000000000000000000 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] 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>
(cherry picked from commit b2740b7e4a03bb8331d48b54b119afea76bb9d5f)
(cherry picked from commit f66ea1e60c347408e92b6695d5105c7e0f24d568)
---
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 a115a63b0c..d0e6340404 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

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0299-font-Fix-integer-overflow-in-BMP-index.patch Normal file
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@ -0,0 +1,64 @@
From 0000000000000000000000000000000000000000 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] 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>
(cherry picked from commit afda8b60ba0712abe01ae1e64c5f7a067a0e6492)
(cherry picked from commit 6d90568929e11739b56f09ebbce9185ca9c23519)
---
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 d0e6340404..b208a28717 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. */

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0300-font-Fix-integer-underflow-in-binary-search-of-char-.patch Normal file
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@ -0,0 +1,84 @@
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Zhang Boyang <zhangboyang.id@gmail.com>
Date: Sun, 14 Aug 2022 18:09:38 +0800
Subject: [PATCH] font: Fix integer underflow in binary search of char index
If search target is less than all entries in font->index then "hi"
variable is set to -1, which translates to SIZE_MAX and leads to errors.
This patch fixes the problem by replacing the entire binary search code
with the libstdc++'s std::lower_bound() implementation.
Signed-off-by: Zhang Boyang <zhangboyang.id@gmail.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
(cherry picked from commit c140a086838e7c9af87842036f891b8393a8c4bc)
(cherry picked from commit e110997335b1744464ea232d57a7d86e16ca8dee)
---
grub-core/font/font.c | 40 ++++++++++++++++++++++------------------
1 file changed, 22 insertions(+), 18 deletions(-)
diff --git a/grub-core/font/font.c b/grub-core/font/font.c
index b208a28717..193dfec045 100644
--- a/grub-core/font/font.c
+++ b/grub-core/font/font.c
@@ -688,12 +688,12 @@ read_be_int16 (grub_file_t file, grub_int16_t * value)
static inline struct char_index_entry *
find_glyph (const grub_font_t font, grub_uint32_t code)
{
- struct char_index_entry *table;
- grub_size_t lo;
- grub_size_t hi;
- grub_size_t mid;
+ struct char_index_entry *table, *first, *end;
+ grub_size_t len;
table = font->char_index;
+ if (table == NULL)
+ return NULL;
/* Use BMP index if possible. */
if (code < 0x10000 && font->bmp_idx)
@@ -706,25 +706,29 @@ find_glyph (const grub_font_t font, grub_uint32_t code)
*/
}
- /* Do a binary search in `char_index', which is ordered by code point. */
- lo = 0;
- hi = font->num_chars - 1;
+ /*
+ * Do a binary search in char_index which is ordered by code point.
+ * The code below is the same as libstdc++'s std::lower_bound().
+ */
+ first = table;
+ len = font->num_chars;
+ end = first + len;
- if (!table)
- return 0;
-
- while (lo <= hi)
+ while (len > 0)
{
- mid = lo + (hi - lo) / 2;
- if (code < table[mid].code)
- hi = mid - 1;
- else if (code > table[mid].code)
- lo = mid + 1;
+ grub_size_t half = len >> 1;
+ struct char_index_entry *middle = first + half;
+
+ if (middle->code < code)
+ {
+ first = middle + 1;
+ len = len - half - 1;
+ }
else
- return &table[mid];
+ len = half;
}
- return 0;
+ return (first < end && first->code == code) ? first : NULL;
}
/* Get a glyph for the Unicode character CODE in FONT. The glyph is loaded

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0301-kern-efi-sb-Enforce-verification-of-font-files.patch Normal file
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@ -0,0 +1,53 @@
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Zhang Boyang <zhangboyang.id@gmail.com>
Date: Sun, 14 Aug 2022 15:51:54 +0800
Subject: [PATCH] kern/efi/sb: Enforce verification of font files
As a mitigation and hardening measure enforce verification of font
files. Then only trusted font files can be load. This will reduce the
attack surface at cost of losing the ability of end-users to customize
fonts if e.g. UEFI Secure Boot is enabled. Vendors can always customize
fonts because they have ability to pack fonts into their GRUB bundles.
This goal is achieved by:
* Removing GRUB_FILE_TYPE_FONT from shim lock verifier's
skip-verification list.
* Adding GRUB_FILE_TYPE_FONT to lockdown verifier's defer-auth list,
so font files must be verified by a verifier before they can be loaded.
Suggested-by: Daniel Kiper <daniel.kiper@oracle.com>
Signed-off-by: Zhang Boyang <zhangboyang.id@gmail.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
(cherry picked from commit 630deb8c0d8b02b670ced4b7030414bcf17aa080)
(cherry picked from commit 37257e0ee45b9029b62f4046c983481d063b821d)
---
grub-core/kern/efi/sb.c | 1 -
grub-core/kern/lockdown.c | 1 +
2 files changed, 1 insertion(+), 1 deletion(-)
diff --git a/grub-core/kern/efi/sb.c b/grub-core/kern/efi/sb.c
index 89c4bb3fd1..db42c2539f 100644
--- a/grub-core/kern/efi/sb.c
+++ b/grub-core/kern/efi/sb.c
@@ -145,7 +145,6 @@ shim_lock_verifier_init (grub_file_t io __attribute__ ((unused)),
case GRUB_FILE_TYPE_PRINT_BLOCKLIST:
case GRUB_FILE_TYPE_TESTLOAD:
case GRUB_FILE_TYPE_GET_SIZE:
- case GRUB_FILE_TYPE_FONT:
case GRUB_FILE_TYPE_ZFS_ENCRYPTION_KEY:
case GRUB_FILE_TYPE_CAT:
case GRUB_FILE_TYPE_HEXCAT:
diff --git a/grub-core/kern/lockdown.c b/grub-core/kern/lockdown.c
index 0bc70fd42d..af6d493cd3 100644
--- a/grub-core/kern/lockdown.c
+++ b/grub-core/kern/lockdown.c
@@ -51,6 +51,7 @@ lockdown_verifier_init (grub_file_t io __attribute__ ((unused)),
case GRUB_FILE_TYPE_EFI_CHAINLOADED_IMAGE:
case GRUB_FILE_TYPE_ACPI_TABLE:
case GRUB_FILE_TYPE_DEVICE_TREE_IMAGE:
+ case GRUB_FILE_TYPE_FONT:
*flags = GRUB_VERIFY_FLAGS_DEFER_AUTH;
/* Fall through. */

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0302-fbutil-Fix-integer-overflow.patch Normal file
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@ -0,0 +1,84 @@
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Zhang Boyang <zhangboyang.id@gmail.com>
Date: Tue, 6 Sep 2022 03:03:21 +0800
Subject: [PATCH] fbutil: Fix integer overflow
Expressions like u64 = u32 * u32 are unsafe because their products are
truncated to u32 even if left hand side is u64. This patch fixes all
problems like that one in fbutil.
To get right result not only left hand side have to be u64 but it's also
necessary to cast at least one of the operands of all leaf operators of
right hand side to u64, e.g. u64 = u32 * u32 + u32 * u32 should be
u64 = (u64)u32 * u32 + (u64)u32 * u32.
For 1-bit bitmaps grub_uint64_t have to be used. It's safe because any
combination of values in (grub_uint64_t)u32 * u32 + u32 expression will
not overflow grub_uint64_t.
Other expressions like ptr + u32 * u32 + u32 * u32 are also vulnerable.
They should be ptr + (grub_addr_t)u32 * u32 + (grub_addr_t)u32 * u32.
This patch also adds a comment to grub_video_fb_get_video_ptr() which
says it's arguments must be valid and no sanity check is performed
(like its siblings in grub-core/video/fb/fbutil.c).
Signed-off-by: Zhang Boyang <zhangboyang.id@gmail.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
(cherry picked from commit 50a11a81bc842c58962244a2dc86bbd31a426e12)
(cherry picked from commit 8fa75d647362c938c4cc302cf5945b31fb92c078)
---
grub-core/video/fb/fbutil.c | 4 ++--
include/grub/fbutil.h | 13 +++++++++----
2 files changed, 11 insertions(+), 6 deletions(-)
diff --git a/grub-core/video/fb/fbutil.c b/grub-core/video/fb/fbutil.c
index b98bb51fe8..25ef39f47d 100644
--- a/grub-core/video/fb/fbutil.c
+++ b/grub-core/video/fb/fbutil.c
@@ -67,7 +67,7 @@ get_pixel (struct grub_video_fbblit_info *source,
case 1:
if (source->mode_info->blit_format == GRUB_VIDEO_BLIT_FORMAT_1BIT_PACKED)
{
- int bit_index = y * source->mode_info->width + x;
+ grub_uint64_t bit_index = (grub_uint64_t) y * source->mode_info->width + x;
grub_uint8_t *ptr = source->data + bit_index / 8;
int bit_pos = 7 - bit_index % 8;
color = (*ptr >> bit_pos) & 0x01;
@@ -138,7 +138,7 @@ set_pixel (struct grub_video_fbblit_info *source,
case 1:
if (source->mode_info->blit_format == GRUB_VIDEO_BLIT_FORMAT_1BIT_PACKED)
{
- int bit_index = y * source->mode_info->width + x;
+ grub_uint64_t bit_index = (grub_uint64_t) y * source->mode_info->width + x;
grub_uint8_t *ptr = source->data + bit_index / 8;
int bit_pos = 7 - bit_index % 8;
*ptr = (*ptr & ~(1 << bit_pos)) | ((color & 0x01) << bit_pos);
diff --git a/include/grub/fbutil.h b/include/grub/fbutil.h
index 4205eb917f..78a1ab3b45 100644
--- a/include/grub/fbutil.h
+++ b/include/grub/fbutil.h
@@ -31,14 +31,19 @@ struct grub_video_fbblit_info
grub_uint8_t *data;
};
-/* Don't use for 1-bit bitmaps, addressing needs to be done at the bit level
- and it doesn't make sense, in general, to ask for a pointer
- to a particular pixel's data. */
+/*
+ * Don't use for 1-bit bitmaps, addressing needs to be done at the bit level
+ * and it doesn't make sense, in general, to ask for a pointer
+ * to a particular pixel's data.
+ *
+ * This function assumes that bounds checking has been done in previous phase
+ * and they are opted out in here.
+ */
static inline void *
grub_video_fb_get_video_ptr (struct grub_video_fbblit_info *source,
unsigned int x, unsigned int y)
{
- return source->data + y * source->mode_info->pitch + x * source->mode_info->bytes_per_pixel;
+ return source->data + (grub_addr_t) y * source->mode_info->pitch + (grub_addr_t) x * source->mode_info->bytes_per_pixel;
}
/* Advance pointer by VAL bytes. If there is no unaligned access available,

90
0303-font-Fix-an-integer-underflow-in-blit_comb.patch Normal file
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@ -0,0 +1,90 @@
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Zhang Boyang <zhangboyang.id@gmail.com>
Date: Mon, 24 Oct 2022 08:05:35 +0800
Subject: [PATCH] font: Fix an integer underflow in blit_comb()
The expression (ctx.bounds.height - combining_glyphs[i]->height) / 2 may
evaluate to a very big invalid value even if both ctx.bounds.height and
combining_glyphs[i]->height are small integers. For example, if
ctx.bounds.height is 10 and combining_glyphs[i]->height is 12, this
expression evaluates to 2147483647 (expected -1). This is because
coordinates are allowed to be negative but ctx.bounds.height is an
unsigned int. So, the subtraction operates on unsigned ints and
underflows to a very big value. The division makes things even worse.
The quotient is still an invalid value even if converted back to int.
This patch fixes the problem by casting ctx.bounds.height to int. As
a result the subtraction will operate on int and grub_uint16_t which
will be promoted to an int. So, the underflow will no longer happen. Other
uses of ctx.bounds.height (and ctx.bounds.width) are also casted to int,
to ensure coordinates are always calculated on signed integers.
Fixes: CVE-2022-3775
Reported-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Zhang Boyang <zhangboyang.id@gmail.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
(cherry picked from commit 6d2668dea3774ed74c4cd1eadd146f1b846bc3d4)
(cherry picked from commit 05e532fb707bbf79aa4e1efbde4d208d7da89d6b)
---
grub-core/font/font.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
diff --git a/grub-core/font/font.c b/grub-core/font/font.c
index 193dfec045..12a5f0d08c 100644
--- a/grub-core/font/font.c
+++ b/grub-core/font/font.c
@@ -1203,12 +1203,12 @@ blit_comb (const struct grub_unicode_glyph *glyph_id,
ctx.bounds.height = main_glyph->height;
above_rightx = main_glyph->offset_x + main_glyph->width;
- above_righty = ctx.bounds.y + ctx.bounds.height;
+ above_righty = ctx.bounds.y + (int) ctx.bounds.height;
above_leftx = main_glyph->offset_x;
- above_lefty = ctx.bounds.y + ctx.bounds.height;
+ above_lefty = ctx.bounds.y + (int) ctx.bounds.height;
- below_rightx = ctx.bounds.x + ctx.bounds.width;
+ below_rightx = ctx.bounds.x + (int) ctx.bounds.width;
below_righty = ctx.bounds.y;
comb = grub_unicode_get_comb (glyph_id);
@@ -1221,7 +1221,7 @@ blit_comb (const struct grub_unicode_glyph *glyph_id,
if (!combining_glyphs[i])
continue;
- targetx = (ctx.bounds.width - combining_glyphs[i]->width) / 2 + ctx.bounds.x;
+ targetx = ((int) ctx.bounds.width - combining_glyphs[i]->width) / 2 + ctx.bounds.x;
/* CGJ is to avoid diacritics reordering. */
if (comb[i].code
== GRUB_UNICODE_COMBINING_GRAPHEME_JOINER)
@@ -1231,8 +1231,8 @@ blit_comb (const struct grub_unicode_glyph *glyph_id,
case GRUB_UNICODE_COMB_OVERLAY:
do_blit (combining_glyphs[i],
targetx,
- (ctx.bounds.height - combining_glyphs[i]->height) / 2
- - (ctx.bounds.height + ctx.bounds.y), &ctx);
+ ((int) ctx.bounds.height - combining_glyphs[i]->height) / 2
+ - ((int) ctx.bounds.height + ctx.bounds.y), &ctx);
if (min_devwidth < combining_glyphs[i]->width)
min_devwidth = combining_glyphs[i]->width;
break;
@@ -1305,7 +1305,7 @@ blit_comb (const struct grub_unicode_glyph *glyph_id,
/* Fallthrough. */
case GRUB_UNICODE_STACK_ATTACHED_ABOVE:
do_blit (combining_glyphs[i], targetx,
- -(ctx.bounds.height + ctx.bounds.y + space
+ -((int) ctx.bounds.height + ctx.bounds.y + space
+ combining_glyphs[i]->height), &ctx);
if (min_devwidth < combining_glyphs[i]->width)
min_devwidth = combining_glyphs[i]->width;
@@ -1313,7 +1313,7 @@ blit_comb (const struct grub_unicode_glyph *glyph_id,
case GRUB_UNICODE_COMB_HEBREW_DAGESH:
do_blit (combining_glyphs[i], targetx,
- -(ctx.bounds.height / 2 + ctx.bounds.y
+ -((int) ctx.bounds.height / 2 + ctx.bounds.y
+ combining_glyphs[i]->height / 2), &ctx);
if (min_devwidth < combining_glyphs[i]->width)
min_devwidth = combining_glyphs[i]->width;

74
0304-font-Harden-grub_font_blit_glyph-and-grub_font_blit_.patch Normal file
View File

@ -0,0 +1,74 @@
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Zhang Boyang <zhangboyang.id@gmail.com>
Date: Mon, 24 Oct 2022 07:15:41 +0800
Subject: [PATCH] font: Harden grub_font_blit_glyph() and
grub_font_blit_glyph_mirror()
As a mitigation and hardening measure add sanity checks to
grub_font_blit_glyph() and grub_font_blit_glyph_mirror(). This patch
makes these two functions do nothing if target blitting area isn't fully
contained in target bitmap. Therefore, if complex calculations in caller
overflows and malicious coordinates are given, we are still safe because
any coordinates which result in out-of-bound-write are rejected. However,
this patch only checks for invalid coordinates, and doesn't provide any
protection against invalid source glyph or destination glyph, e.g.
mismatch between glyph size and buffer size.
This hardening measure is designed to mitigate possible overflows in
blit_comb(). If overflow occurs, it may return invalid bounding box
during dry run and call grub_font_blit_glyph() with malicious
coordinates during actual blitting. However, we are still safe because
the scratch glyph itself is valid, although its size makes no sense, and
any invalid coordinates are rejected.
It would be better to call grub_fatal() if illegal parameter is detected.
However, doing this may end up in a dangerous recursion because grub_fatal()
would print messages to the screen and we are in the progress of drawing
characters on the screen.
Reported-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Zhang Boyang <zhangboyang.id@gmail.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
(cherry picked from commit fcd7aa0c278f7cf3fb9f93f1a3966e1792339eb6)
(cherry picked from commit 1d37ec63a1c76a14fdf70f548eada92667b42ddb)
---
grub-core/font/font.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/grub-core/font/font.c b/grub-core/font/font.c
index 12a5f0d08c..29fbb94294 100644
--- a/grub-core/font/font.c
+++ b/grub-core/font/font.c
@@ -1069,8 +1069,15 @@ static void
grub_font_blit_glyph (struct grub_font_glyph *target,
struct grub_font_glyph *src, unsigned dx, unsigned dy)
{
+ grub_uint16_t max_x, max_y;
unsigned src_bit, tgt_bit, src_byte, tgt_byte;
unsigned i, j;
+
+ /* Harden against out-of-bound writes. */
+ if ((grub_add (dx, src->width, &max_x) || max_x > target->width) ||
+ (grub_add (dy, src->height, &max_y) || max_y > target->height))
+ return;
+
for (i = 0; i < src->height; i++)
{
src_bit = (src->width * i) % 8;
@@ -1102,9 +1109,16 @@ grub_font_blit_glyph_mirror (struct grub_font_glyph *target,
struct grub_font_glyph *src,
unsigned dx, unsigned dy)
{
+ grub_uint16_t max_x, max_y;
unsigned tgt_bit, src_byte, tgt_byte;
signed src_bit;
unsigned i, j;
+
+ /* Harden against out-of-bound writes. */
+ if ((grub_add (dx, src->width, &max_x) || max_x > target->width) ||
+ (grub_add (dy, src->height, &max_y) || max_y > target->height))
+ return;
+
for (i = 0; i < src->height; i++)
{
src_bit = (src->width * i + src->width - 1) % 8;

35
0305-font-Assign-null_font-to-glyphs-in-ascii_font_glyph.patch Normal file
View File

@ -0,0 +1,35 @@
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Zhang Boyang <zhangboyang.id@gmail.com>
Date: Fri, 28 Oct 2022 17:29:16 +0800
Subject: [PATCH] font: Assign null_font to glyphs in ascii_font_glyph[]
The calculations in blit_comb() need information from glyph's font, e.g.
grub_font_get_xheight(main_glyph->font). However, main_glyph->font is
NULL if main_glyph comes from ascii_font_glyph[]. Therefore
grub_font_get_*() crashes because of NULL pointer.
There is already a solution, the null_font. So, assign it to those glyphs
in ascii_font_glyph[].
Reported-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Zhang Boyang <zhangboyang.id@gmail.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
(cherry picked from commit dd539d695482069d28b40f2d3821f710cdcf6ee6)
(cherry picked from commit 87526376857eaceae474c9797e3cee5b50597332)
---
grub-core/font/font.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/grub-core/font/font.c b/grub-core/font/font.c
index 29fbb94294..e6616e610c 100644
--- a/grub-core/font/font.c
+++ b/grub-core/font/font.c
@@ -137,7 +137,7 @@ ascii_glyph_lookup (grub_uint32_t code)
ascii_font_glyph[current]->offset_x = 0;
ascii_font_glyph[current]->offset_y = -2;
ascii_font_glyph[current]->device_width = 8;
- ascii_font_glyph[current]->font = NULL;
+ ascii_font_glyph[current]->font = &null_font;
grub_memcpy (ascii_font_glyph[current]->bitmap,
&ascii_bitmaps[current * ASCII_BITMAP_SIZE],

54
0306-normal-charset-Fix-an-integer-overflow-in-grub_unico.patch Normal file
View File

@ -0,0 +1,54 @@
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Zhang Boyang <zhangboyang.id@gmail.com>
Date: Fri, 28 Oct 2022 21:31:39 +0800
Subject: [PATCH] normal/charset: Fix an integer overflow in
grub_unicode_aglomerate_comb()
The out->ncomb is a bit-field of 8 bits. So, the max possible value is 255.
However, code in grub_unicode_aglomerate_comb() doesn't check for an
overflow when incrementing out->ncomb. If out->ncomb is already 255,
after incrementing it will get 0 instead of 256, and cause illegal
memory access in subsequent processing.
This patch introduces GRUB_UNICODE_NCOMB_MAX to represent the max
acceptable value of ncomb. The code now checks for this limit and
ignores additional combining characters when limit is reached.
Reported-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Zhang Boyang <zhangboyang.id@gmail.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
(cherry picked from commit da90d62316a3b105d2fbd7334d6521936bd6dcf6)
(cherry picked from commit 26fafec86000b5322837722a115279ef03922ca6)
---
grub-core/normal/charset.c | 3 +++
include/grub/unicode.h | 2 ++
2 files changed, 5 insertions(+)
diff --git a/grub-core/normal/charset.c b/grub-core/normal/charset.c
index 7a5a7c153c..c243ca6dae 100644
--- a/grub-core/normal/charset.c
+++ b/grub-core/normal/charset.c
@@ -472,6 +472,9 @@ grub_unicode_aglomerate_comb (const grub_uint32_t *in, grub_size_t inlen,
if (!haveout)
continue;
+ if (out->ncomb == GRUB_UNICODE_NCOMB_MAX)
+ continue;
+
if (comb_type == GRUB_UNICODE_COMB_MC
|| comb_type == GRUB_UNICODE_COMB_ME
|| comb_type == GRUB_UNICODE_COMB_MN)
diff --git a/include/grub/unicode.h b/include/grub/unicode.h
index 4de986a857..c4f6fca043 100644
--- a/include/grub/unicode.h
+++ b/include/grub/unicode.h
@@ -147,7 +147,9 @@ struct grub_unicode_glyph
grub_uint8_t bidi_level:6; /* minimum: 6 */
enum grub_bidi_type bidi_type:5; /* minimum: :5 */
+#define GRUB_UNICODE_NCOMB_MAX ((1 << 8) - 1)
unsigned ncomb:8;
+
/* Hint by unicode subsystem how wide this character usually is.
Real width is determined by font. Set only in UTF-8 stream. */
int estimated_width:8;

13
grub.patches
View File

@ -291,3 +291,16 @@ Patch0290: 0290-x86-efi-Fix-an-incorrect-array-size-in-kernel-alloca.patch
Patch0291: 0291-commands-efi-tpm-Refine-the-status-of-log-event.patch
Patch0292: 0292-commands-efi-tpm-Use-grub_strcpy-instead-of-grub_mem.patch
Patch0293: 0293-efi-tpm-Add-EFI_CC_MEASUREMENT_PROTOCOL-support.patch
Patch0294: 0294-font-Reject-glyphs-exceeds-font-max_glyph_width-or-f.patch
Patch0295: 0295-font-Fix-size-overflow-in-grub_font_get_glyph_intern.patch
Patch0296: 0296-font-Fix-several-integer-overflows-in-grub_font_cons.patch
Patch0297: 0297-font-Remove-grub_font_dup_glyph.patch
Patch0298: 0298-font-Fix-integer-overflow-in-ensure_comb_space.patch
Patch0299: 0299-font-Fix-integer-overflow-in-BMP-index.patch
Patch0300: 0300-font-Fix-integer-underflow-in-binary-search-of-char-.patch
Patch0301: 0301-kern-efi-sb-Enforce-verification-of-font-files.patch
Patch0302: 0302-fbutil-Fix-integer-overflow.patch
Patch0303: 0303-font-Fix-an-integer-underflow-in-blit_comb.patch
Patch0304: 0304-font-Harden-grub_font_blit_glyph-and-grub_font_blit_.patch
Patch0305: 0305-font-Assign-null_font-to-glyphs-in-ascii_font_glyph.patch
Patch0306: 0306-normal-charset-Fix-an-integer-overflow-in-grub_unico.patch

6
grub2.spec
View File

@ -14,7 +14,7 @@
Name: grub2
Epoch: 1
Version: 2.06
Release: 48%{?dist}
Release: 49%{?dist}
Summary: Bootloader with support for Linux, Multiboot and more
License: GPLv3+
URL: http://www.gnu.org/software/grub/
@ -532,6 +532,10 @@ mv ${EFI_HOME}/grub.cfg.stb ${EFI_HOME}/grub.cfg
%endif
%changelog
* Thu Nov 03 2022 Robbie Harwood <rharwood@redhat.com> - 1:2.06-49
- Font CVE fixes
- Resolves: CVE-2022-2601
* Fri Oct 28 2022 Robbie Harwood <rharwood@redhat.com> - 1:2.06-48
- TDX measurement to RTMR
- Resolves: #1981487