Andrew Geissler | 517393d | 2023-01-13 08:55:19 -0600 | [diff] [blame^] | 1 | From 1f511ae054fe42dce7aedfbfe0f234fa1e0a7a3e Mon Sep 17 00:00:00 2001 |
| 2 | From: Zhang Boyang <zhangboyang.id@gmail.com> |
| 3 | Date: Fri, 5 Aug 2022 00:51:20 +0800 |
| 4 | Subject: [PATCH] font: Fix size overflow in grub_font_get_glyph_internal() |
| 5 | |
| 6 | The length of memory allocation and file read may overflow. This patch |
| 7 | fixes the problem by using safemath macros. |
| 8 | |
| 9 | There is a lot of code repetition like "(x * y + 7) / 8". It is unsafe |
| 10 | if overflow happens. This patch introduces grub_video_bitmap_calc_1bpp_bufsz(). |
| 11 | It is safe replacement for such code. It has safemath-like prototype. |
| 12 | |
| 13 | This patch also introduces grub_cast(value, pointer), it casts value to |
| 14 | typeof(*pointer) then store the value to *pointer. It returns true when |
| 15 | overflow occurs or false if there is no overflow. The semantics of arguments |
| 16 | and return value are designed to be consistent with other safemath macros. |
| 17 | |
| 18 | Signed-off-by: Zhang Boyang <zhangboyang.id@gmail.com> |
| 19 | Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com> |
| 20 | |
| 21 | Upstream-Status: Backport from |
| 22 | [https://git.savannah.gnu.org/cgit/grub.git/commit/?id=9c76ec09ae08155df27cd237eaea150b4f02f532] |
| 23 | |
| 24 | Signed-off-by: Xiangyu Chen <xiangyu.chen@windriver.com> |
| 25 | |
| 26 | --- |
| 27 | grub-core/font/font.c | 17 +++++++++++++---- |
| 28 | include/grub/bitmap.h | 18 ++++++++++++++++++ |
| 29 | include/grub/safemath.h | 2 ++ |
| 30 | 3 files changed, 33 insertions(+), 4 deletions(-) |
| 31 | |
| 32 | diff --git a/grub-core/font/font.c b/grub-core/font/font.c |
| 33 | index d09bb38..876b5b6 100644 |
| 34 | --- a/grub-core/font/font.c |
| 35 | +++ b/grub-core/font/font.c |
| 36 | @@ -739,7 +739,8 @@ grub_font_get_glyph_internal (grub_font_t font, grub_uint32_t code) |
| 37 | grub_int16_t xoff; |
| 38 | grub_int16_t yoff; |
| 39 | grub_int16_t dwidth; |
| 40 | - int len; |
| 41 | + grub_ssize_t len; |
| 42 | + grub_size_t sz; |
| 43 | |
| 44 | if (index_entry->glyph) |
| 45 | /* Return cached glyph. */ |
| 46 | @@ -766,9 +767,17 @@ grub_font_get_glyph_internal (grub_font_t font, grub_uint32_t code) |
| 47 | return 0; |
| 48 | } |
| 49 | |
| 50 | - len = (width * height + 7) / 8; |
| 51 | - glyph = grub_malloc (sizeof (struct grub_font_glyph) + len); |
| 52 | - if (!glyph) |
| 53 | + /* Calculate real struct size of current glyph. */ |
| 54 | + if (grub_video_bitmap_calc_1bpp_bufsz (width, height, &len) || |
| 55 | + grub_add (sizeof (struct grub_font_glyph), len, &sz)) |
| 56 | + { |
| 57 | + remove_font (font); |
| 58 | + return 0; |
| 59 | + } |
| 60 | + |
| 61 | + /* Allocate and initialize the glyph struct. */ |
| 62 | + glyph = grub_malloc (sz); |
| 63 | + if (glyph == NULL) |
| 64 | { |
| 65 | remove_font (font); |
| 66 | return 0; |
| 67 | diff --git a/include/grub/bitmap.h b/include/grub/bitmap.h |
| 68 | index 5728f8c..0d9603f 100644 |
| 69 | --- a/include/grub/bitmap.h |
| 70 | +++ b/include/grub/bitmap.h |
| 71 | @@ -23,6 +23,7 @@ |
| 72 | #include <grub/symbol.h> |
| 73 | #include <grub/types.h> |
| 74 | #include <grub/video.h> |
| 75 | +#include <grub/safemath.h> |
| 76 | |
| 77 | struct grub_video_bitmap |
| 78 | { |
| 79 | @@ -79,6 +80,23 @@ grub_video_bitmap_get_height (struct grub_video_bitmap *bitmap) |
| 80 | return bitmap->mode_info.height; |
| 81 | } |
| 82 | |
| 83 | +/* |
| 84 | + * Calculate and store the size of data buffer of 1bit bitmap in result. |
| 85 | + * Equivalent to "*result = (width * height + 7) / 8" if no overflow occurs. |
| 86 | + * Return true when overflow occurs or false if there is no overflow. |
| 87 | + * This function is intentionally implemented as a macro instead of |
| 88 | + * an inline function. Although a bit awkward, it preserves data types for |
| 89 | + * safemath macros and reduces macro side effects as much as possible. |
| 90 | + * |
| 91 | + * XXX: Will report false overflow if width * height > UINT64_MAX. |
| 92 | + */ |
| 93 | +#define grub_video_bitmap_calc_1bpp_bufsz(width, height, result) \ |
| 94 | +({ \ |
| 95 | + grub_uint64_t _bitmap_pixels; \ |
| 96 | + grub_mul ((width), (height), &_bitmap_pixels) ? 1 : \ |
| 97 | + grub_cast (_bitmap_pixels / GRUB_CHAR_BIT + !!(_bitmap_pixels % GRUB_CHAR_BIT), (result)); \ |
| 98 | +}) |
| 99 | + |
| 100 | void EXPORT_FUNC (grub_video_bitmap_get_mode_info) (struct grub_video_bitmap *bitmap, |
| 101 | struct grub_video_mode_info *mode_info); |
| 102 | |
| 103 | diff --git a/include/grub/safemath.h b/include/grub/safemath.h |
| 104 | index c17b89b..bb0f826 100644 |
| 105 | --- a/include/grub/safemath.h |
| 106 | +++ b/include/grub/safemath.h |
| 107 | @@ -30,6 +30,8 @@ |
| 108 | #define grub_sub(a, b, res) __builtin_sub_overflow(a, b, res) |
| 109 | #define grub_mul(a, b, res) __builtin_mul_overflow(a, b, res) |
| 110 | |
| 111 | +#define grub_cast(a, res) grub_add ((a), 0, (res)) |
| 112 | + |
| 113 | #else |
| 114 | #error gcc 5.1 or newer or clang 3.8 or newer is required |
| 115 | #endif |