From d2a96dd89c0f0c5da62974439d74b7b351c0dbaf Mon Sep 17 00:00:00 2001 From: Yogita Urade Date: Fri, 19 Sep 2025 13:53:26 +0530 Subject: grub2: fix CVE-2024-56738 Backport an algorithmic change to grub_crypto_memcmp() so that it completes in constant time and thus isn't susceptible to side-channel attacks. reference: https://git.openembedded.org/openembedded-core/commit/?id=30a1cc225a2bd5d044bf608d863a67df3f9c03be Upstream patch: https://cgit.git.savannah.gnu.org/cgit/grub.git/commit/?id=0739d24cd1648531d0708d1079ff6bbfa6140268 (From OE-Core rev: d6572d29892b7da593acafe3af68cf98230acf04) Signed-off-by: Yogita Urade Signed-off-by: Steve Sakoman --- meta/recipes-bsp/grub/files/CVE-2024-56738.patch | 75 ++++++++++++++++++++++++ meta/recipes-bsp/grub/grub2.inc | 1 + 2 files changed, 76 insertions(+) create mode 100644 meta/recipes-bsp/grub/files/CVE-2024-56738.patch diff --git a/meta/recipes-bsp/grub/files/CVE-2024-56738.patch b/meta/recipes-bsp/grub/files/CVE-2024-56738.patch new file mode 100644 index 0000000000..1212b2d3e5 --- /dev/null +++ b/meta/recipes-bsp/grub/files/CVE-2024-56738.patch @@ -0,0 +1,75 @@ +From 4cef2fc7308b2132317ad166939994f098b41561 Mon Sep 17 00:00:00 2001 +From: Ross Burton +Date: Tue, 9 Sep 2025 14:23:14 +0100 +Subject: [PATCH] CVE-2024-56738 + +Backport an algorithmic change to grub_crypto_memcmp() so that it completes in +constant time and thus isn't susceptible to side-channel attacks. + +This is a partial backport of grub 0739d24cd +("libgcrypt: Adjust import script, definitions and API users for libgcrypt 1.11") + +CVE: CVE-2024-56738 +Upstream-Status: Backport [0739d24cd] +Signed-off-by: Ross Burton +Signed-off-by: Yogita Urade +--- + grub-core/lib/crypto.c | 23 ++++++++++++++++------- + include/grub/crypto.h | 2 +- + 2 files changed, 17 insertions(+), 8 deletions(-) + +diff --git a/grub-core/lib/crypto.c b/grub-core/lib/crypto.c +index ca334d5..1bfa922 100644 +--- a/grub-core/lib/crypto.c ++++ b/grub-core/lib/crypto.c +@@ -433,19 +433,28 @@ grub_crypto_gcry_error (gcry_err_code_t in) + return GRUB_ACCESS_DENIED; + } + ++/* ++ * Compare byte arrays of length LEN, return 1 if it's not same, ++ * 0, otherwise. ++ */ + int +-grub_crypto_memcmp (const void *a, const void *b, grub_size_t n) ++grub_crypto_memcmp (const void *b1, const void *b2, grub_size_t len) + { +- register grub_size_t counter = 0; +- const grub_uint8_t *pa, *pb; ++ const grub_uint8_t *a = b1; ++ const grub_uint8_t *b = b2; ++ int ab, ba; ++ grub_size_t i; + +- for (pa = a, pb = b; n; pa++, pb++, n--) ++ /* Constant-time compare. */ ++ for (i = 0, ab = 0, ba = 0; i < len; i++) + { +- if (*pa != *pb) +- counter++; ++ /* If a[i] != b[i], either ab or ba will be negative. */ ++ ab |= a[i] - b[i]; ++ ba |= b[i] - a[i]; + } + +- return !!counter; ++ /* 'ab | ba' is negative when buffers are not equal, extract sign bit. */ ++ return ((unsigned int)(ab | ba) >> (sizeof(unsigned int) * 8 - 1)) & 1; + } + + #ifndef GRUB_UTIL +diff --git a/include/grub/crypto.h b/include/grub/crypto.h +index 21cd1f7..432912b 100644 +--- a/include/grub/crypto.h ++++ b/include/grub/crypto.h +@@ -393,7 +393,7 @@ grub_crypto_pbkdf2 (const struct gcry_md_spec *md, + grub_uint8_t *DK, grub_size_t dkLen); + + int +-grub_crypto_memcmp (const void *a, const void *b, grub_size_t n); ++grub_crypto_memcmp (const void *b1, const void *b2, grub_size_t len); + + int + grub_password_get (char buf[], unsigned buf_size); +-- +2.40.0 diff --git a/meta/recipes-bsp/grub/grub2.inc b/meta/recipes-bsp/grub/grub2.inc index cb61080aeb..1b019752b7 100644 --- a/meta/recipes-bsp/grub/grub2.inc +++ b/meta/recipes-bsp/grub/grub2.inc @@ -59,6 +59,7 @@ SRC_URI = "${GNU_MIRROR}/grub/grub-${PV}.tar.gz \ file://CVE-2025-0678_CVE-2025-1125.patch \ file://CVE-2025-0690.patch \ file://CVE-2025-1118.patch \ + file://CVE-2024-56738.patch \ " SRC_URI[sha256sum] = "23b64b4c741569f9426ed2e3d0e6780796fca081bee4c99f62aa3f53ae803f5f" -- cgit v1.2.3-54-g00ecf