From 7df766124f87768b43b9e8947c5a01e17545772c Mon Sep 17 00:00:00 2001 From: Dmitry Belyavskiy Date: Sat, 21 May 2022 20:06:47 +0200 Subject: [PATCH] Fix buffer overrun in creating key transport blob according to RFC 9189, 4.2.4.2 Resolves: CVE-2022-29242 --- gost_ec_keyx.c | 22 +++++++++++++++++++++- 1 file changed, 21 insertions(+), 1 deletion(-) diff --git a/gost_ec_keyx.c b/gost_ec_keyx.c index 5e677dc..192b892 100644 --- a/gost_ec_keyx.c +++ b/gost_ec_keyx.c @@ -292,6 +292,8 @@ static int pkey_GOST_ECcp_encrypt(EVP_PKEY_CTX *pctx, unsigned char *out, int key_is_ephemeral = 1; gost_ctx cctx; EVP_PKEY *sec_key = EVP_PKEY_CTX_get0_peerkey(pctx); + int res_len = 0; + if (data->shared_ukm_size) { memcpy(ukm, data->shared_ukm, 8); } else { @@ -373,8 +375,26 @@ static int pkey_GOST_ECcp_encrypt(EVP_PKEY_CTX *pctx, unsigned char *out, goto err; } } - if ((*out_len = i2d_GOST_KEY_TRANSPORT(gkt, out ? &out : NULL)) > 0) + res_len = i2d_GOST_KEY_TRANSPORT(gkt, NULL); + if (res_len <= 0) { + GOSTerr(GOST_F_PKEY_GOST_ECCP_ENCRYPT, ERR_R_ASN1_LIB); + goto err; + } + + if (out == NULL) { + *out_len = res_len; ret = 1; + } else { + if ((size_t)res_len > *out_len) { + GOSTerr(GOST_F_PKEY_GOST_ECCP_ENCRYPT, GOST_R_INVALID_BUFFER_SIZE); + goto err; + } + if ((*out_len = i2d_GOST_KEY_TRANSPORT(gkt, &out)) > 0) + ret = 1; + else + GOSTerr(GOST_F_PKEY_GOST_ECCP_ENCRYPT, ERR_R_ASN1_LIB); + } + OPENSSL_cleanse(shared_key, sizeof(shared_key)); GOST_KEY_TRANSPORT_free(gkt); return ret; -- 2.39.2