From: Pauli <pauli@openssl.org>
Date: Tue, 26 Jul 2022 01:46:45 +0000 (+1000)
Subject: Fix bug in EVP_CIPHER_CTX_get_iv_length()
X-Git-Tag: openssl-3.2.0-alpha1~2305
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e0e338c8c50c226efc92fe79c788c9cdc03fc01f;p=thirdparty%2Fopenssl.git

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 32482b733f8..98bb25655d7 100644
--- 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)