From 1514678888595ef41a968a0c69b7ff769edd1e9c Mon Sep 17 00:00:00 2001 From: Zhang Boyang Date: Fri, 28 Oct 2022 21:31:39 +0800 Subject: [PATCH 12/12] 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 Signed-off-by: Zhang Boyang Reviewed-by: Daniel Kiper --- 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 000e687bd..4f6647116 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 71a4d1a54..9360b0b97 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; -- 2.33.5