rands/drbg_hmac.c: Add checks for the EVP_MD_get_size()

Add checks for the EVP_MD_get_size() to avoid integer overflow and then explicitly cast from int to size_t.

Fixes: 8bf3665196 ("Added DRBG_HMAC & DRBG_HASH + Added defaults for setting DRBG for master/public/private + renamed generate_counter back to reseed_counter + generated new cavs data tests")
Signed-off-by: Jiasheng Jiang <jiasheng@purdue.edu>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Paul Dale <ppzgs1@gmail.com>
Reviewed-by: Tom Cosgrove <tom.cosgrove@arm.com>
Reviewed-by: Neil Horman <nhorman@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/23945)

diff --git a/providers/implementations/rands/drbg_hmac.c b/providers/implementations/rands/drbg_hmac.c
index bc8a4ff57859cfef467bef45931ac8b50924d7ec..3cd1b614e022b713bfa2663fb3af88b7f79a4fec 100644 (file)
--- a/providers/implementations/rands/drbg_hmac.c
+++ b/providers/implementations/rands/drbg_hmac.c
@@ -410,6 +410,7 @@ static int drbg_hmac_set_ctx_params_locked(void *vctx, const OSSL_PARAM params[]
     PROV_DRBG_HMAC *hmac = (PROV_DRBG_HMAC *)ctx->data;
     OSSL_LIB_CTX *libctx = PROV_LIBCTX_OF(ctx->provctx);
     const EVP_MD *md;
+    int md_size;
 
     if (!ossl_prov_digest_load_from_params(&hmac->digest, params, libctx))
         return 0;
@@ -424,7 +425,10 @@ static int drbg_hmac_set_ctx_params_locked(void *vctx, const OSSL_PARAM params[]
 
     if (md != NULL && hmac->ctx != NULL) {
         /* These are taken from SP 800-90 10.1 Table 2 */
-        hmac->blocklen = EVP_MD_get_size(md);
+        md_size = EVP_MD_get_size(md);
+        if (md_size <= 0)
+            return 0;
+        hmac->blocklen = (size_t)md_size;
         /* See SP800-57 Part1 Rev4 5.6.1 Table 3 */
         ctx->strength = 64 * (int)(hmac->blocklen >> 3);
         if (ctx->strength > 256)