Fix bug in EVP_CIPHER_CTX_get_iv_length()

Out of range values could possibly be returned due to a lack of range checking.
Very unlikely to be exploitable for our provider because sensible values are
returned for all ciphers.

Also fixed the defaulting code so that the cipher's IV length is returned if
the cipher ctx doesn't support getting.

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Dmitry Belyavskiy <beldmit@gmail.com>
(Merged from https://github.com/openssl/openssl/pull/18875)

diff --git a/crypto/evp/evp_lib.c b/crypto/evp/evp_lib.c
index 32482b733f85ac78947a0ee584bc2e60287270b5..98bb25655d713bcaffc6de9544482d3ceaa9783f 100644 (file)
--- a/crypto/evp/evp_lib.c
+++ b/crypto/evp/evp_lib.c
@@ -509,12 +509,17 @@ int EVP_CIPHER_CTX_get_iv_length(const EVP_CIPHER_CTX *ctx)
         size_t v = len;
         OSSL_PARAM params[2] = { OSSL_PARAM_END, OSSL_PARAM_END };
 
-        params[0] = OSSL_PARAM_construct_size_t(OSSL_CIPHER_PARAM_IVLEN, &v);
-        rv = evp_do_ciph_ctx_getparams(ctx->cipher, ctx->algctx, params);
-        if (rv != EVP_CTRL_RET_UNSUPPORTED) {
-            if (rv <= 0)
+        if (ctx->cipher->get_ctx_params != NULL) {
+            params[0] = OSSL_PARAM_construct_size_t(OSSL_CIPHER_PARAM_IVLEN,
+                                                    &v);
+            rv = evp_do_ciph_ctx_getparams(ctx->cipher, ctx->algctx, params);
+            if (rv > 0) {
+                if (OSSL_PARAM_modified(params)
+                        && !OSSL_PARAM_get_int(params, &len))
+                    return -1;
+            } else if (rv != EVP_CTRL_RET_UNSUPPORTED) {
                 return -1;
-            len = (int)v;
+            }
         }
         /* Code below to be removed when legacy support is dropped. */
         else if ((EVP_CIPHER_get_flags(ctx->cipher)