From 768e1ef2fc159f6e14e7246e4be09363708ac39e Mon Sep 17 00:00:00 2001 From: Zhang Boyang Date: Fri, 5 Aug 2022 01:58:27 +0800 Subject: [PATCH 02/12] 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 Signed-off-by: Zhang Boyang Reviewed-by: Daniel Kiper --- 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 e781521a7..e6548892f 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, -- 2.33.5