francis.wang
4c86c082a2
Combine poky (Yocto scarthgap), meta-openembedded (scarthgap), and meta-openwrt into a single repository. Components: - poky/ Yocto core framework (BitBake + OE-Core) - meta-openembedded/ Community layers (meta-oe, meta-python, meta-networking) - meta-openwrt/ OpenWrt customization layer - setup-env.sh One-click build environment setup - README.md Project documentation
76 lines
2.3 KiB
Diff
76 lines
2.3 KiB
Diff
From 4cef2fc7308b2132317ad166939994f098b41561 Mon Sep 17 00:00:00 2001
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From: Ross Burton <ross.burton@arm.com>
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Date: Tue, 9 Sep 2025 14:23:14 +0100
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Subject: [PATCH] CVE-2024-56738
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Backport an algorithmic change to grub_crypto_memcmp() so that it completes in
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constant time and thus isn't susceptible to side-channel attacks.
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This is a partial backport of grub 0739d24cd
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("libgcrypt: Adjust import script, definitions and API users for libgcrypt 1.11")
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CVE: CVE-2024-56738
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Upstream-Status: Backport [0739d24cd]
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Signed-off-by: Ross Burton <ross.burton@arm.com>
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---
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grub-core/lib/crypto.c | 23 ++++++++++++++++-------
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include/grub/crypto.h | 2 +-
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2 files changed, 17 insertions(+), 8 deletions(-)
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diff --git a/grub-core/lib/crypto.c b/grub-core/lib/crypto.c
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index 396f76410..19db7870a 100644
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--- a/grub-core/lib/crypto.c
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+++ b/grub-core/lib/crypto.c
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@@ -433,19 +433,28 @@ grub_crypto_gcry_error (gcry_err_code_t in)
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return GRUB_ACCESS_DENIED;
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}
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+/*
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+ * Compare byte arrays of length LEN, return 1 if it's not same,
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+ * 0, otherwise.
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+ */
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int
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-grub_crypto_memcmp (const void *a, const void *b, grub_size_t n)
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+grub_crypto_memcmp (const void *b1, const void *b2, grub_size_t len)
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{
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- register grub_size_t counter = 0;
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- const grub_uint8_t *pa, *pb;
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+ const grub_uint8_t *a = b1;
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+ const grub_uint8_t *b = b2;
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+ int ab, ba;
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+ grub_size_t i;
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- for (pa = a, pb = b; n; pa++, pb++, n--)
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+ /* Constant-time compare. */
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+ for (i = 0, ab = 0, ba = 0; i < len; i++)
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{
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- if (*pa != *pb)
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- counter++;
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+ /* If a[i] != b[i], either ab or ba will be negative. */
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+ ab |= a[i] - b[i];
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+ ba |= b[i] - a[i];
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}
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- return !!counter;
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+ /* 'ab | ba' is negative when buffers are not equal, extract sign bit. */
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+ return ((unsigned int)(ab | ba) >> (sizeof(unsigned int) * 8 - 1)) & 1;
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}
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#ifndef GRUB_UTIL
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diff --git a/include/grub/crypto.h b/include/grub/crypto.h
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index 31c87c302..20ad4c5f7 100644
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--- a/include/grub/crypto.h
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+++ b/include/grub/crypto.h
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@@ -393,7 +393,7 @@ grub_crypto_pbkdf2 (const struct gcry_md_spec *md,
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grub_uint8_t *DK, grub_size_t dkLen);
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int
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-grub_crypto_memcmp (const void *a, const void *b, grub_size_t n);
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+grub_crypto_memcmp (const void *b1, const void *b2, grub_size_t len);
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int
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grub_password_get (char buf[], unsigned buf_size);
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--
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2.43.0
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