From 7aee873d6f6b0737dfe566fc8c5cd4eaada9bd5e Mon Sep 17 00:00:00 2001 From: Fabrice Fontaine Date: Mon, 8 Apr 2024 11:56:06 +0200 Subject: [PATCH] cmac.c: optimize make_kn and move zero_iv to const segment. Backport https:\/\/github.com\/openssl\/openssl\/commit\/03cf7e784caa4c61febbf249be63cbae3e368ac9 to fix the following k1 stringop-overflow: In function 'make_kn', inlined from 'make_kn' at crypto\/cmac\/cmac.c:81:13, inlined from 'CMAC_Init' at crypto\/cmac\/cmac.c:205:9: crypto\/cmac\/cmac.c:92:20: error: writing 1 byte into a region of size 0 [-Werror=stringop-overflow=] 92 | k1[bl - 1] ^= bl == 16 ? 0x87 : 0x1b; | ~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~ crypto\/cmac\/cmac.c: In function 'CMAC_Init': crypto\/cmac\/cmac.c:69:19: note: at offset [-2147483649, -1] into destination object 'k1' of size 32 69 | unsigned char k1[EVP_MAX_BLOCK_LENGTH]; | ^~ Fixes: - http:\/\/autobuild.buildroot.org\/results\/97b6333cdc7bad24aba7af1b04890679e0058299 Upstream: https:\/\/github.com\/rhboot\/shim\/pull\/652 Signed-off-by: Fabrice Fontaine Signed-off-by: Peter Korsgaard --- Cryptlib\/OpenSSL\/crypto\/cmac\/cmac.c | 17 ++++++++--------- 1 file changed, 8 insertions(+), 9 deletions(-) diff --git a\/Cryptlib\/OpenSSL\/crypto\/cmac\/cmac.c b\/Cryptlib\/OpenSSL\/crypto\/cmac\/cmac.c index 2954b6eb..27dbfaac 100644 --- a\/Cryptlib\/OpenSSL\/crypto\/cmac\/cmac.c +++ b\/Cryptlib\/OpenSSL\/crypto\/cmac\/cmac.c @@ -78,18 +78,17 @@ struct CMAC_CTX_st { \/* Make temporary keys K1 and K2 *\/ -static void make_kn(unsigned char *k1, unsigned char *l, int bl) +static void make_kn(unsigned char *k1, const unsigned char *l, int bl) { int i; + unsigned char c = l[0], carry = c>>7, cnext; + \/* Shift block to left, including carry *\/ - for (i = 0; i < bl; i++) { - k1[i] = l[i] << 1; - if (i < bl - 1 && l[i + 1] & 0x80) - k1[i] |= 1; - } + for (i = 0; i < bl-1; i++, c = cnext) + k1[i] = (c << 1) | ((cnext=l[i+1]) >> 7); + \/* If MSB set fixup with R *\/ - if (l[0] & 0x80) - k1[bl - 1] ^= bl == 16 ? 0x87 : 0x1b; + k1[i] = (c << 1) ^ ((0-carry)&(bl==16?0x87:0x1b)); } CMAC_CTX *CMAC_CTX_new(void) @@ -151,7 +150,7 @@ int CMAC_CTX_copy(CMAC_CTX *out, const CMAC_CTX *in) int CMAC_Init(CMAC_CTX *ctx, const void *key, size_t keylen, const EVP_CIPHER *cipher, ENGINE *impl) { - static unsigned char zero_iv[EVP_MAX_BLOCK_LENGTH]; + static const unsigned char zero_iv[EVP_MAX_BLOCK_LENGTH] = {0}; #ifdef OPENSSL_FIPS if (FIPS_mode()) { \/* If we have an ENGINE need to allow non FIPS *\/ -- 2.47.3

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