Don't directly access iv_size

Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>
diff --git a/library/cipher.c b/library/cipher.c
index 7dc09ee..dfbbbfd 100644
--- a/library/cipher.c
+++ b/library/cipher.c
@@ -375,7 +375,7 @@
     if ((ctx->cipher_info->flags & MBEDTLS_CIPHER_VARIABLE_IV_LEN) != 0) {
         actual_iv_size = iv_len;
     } else {
-        actual_iv_size = ctx->cipher_info->iv_size;
+        actual_iv_size = mbedtls_cipher_info_get_iv_size(ctx->cipher_info);
 
         /* avoid reading past the end of input buffer */
         if (actual_iv_size > iv_len) {
@@ -1363,7 +1363,7 @@
 #if defined(MBEDTLS_CHACHAPOLY_C)
     if (MBEDTLS_CIPHER_CHACHA20_POLY1305 == ctx->cipher_info->type) {
         /* ChachaPoly has fixed length nonce and MAC (tag) */
-        if ((iv_len != ctx->cipher_info->iv_size) ||
+        if ((iv_len != mbedtls_cipher_info_get_iv_size(ctx->cipher_info)) ||
             (tag_len != 16U)) {
             return MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA;
         }
@@ -1459,7 +1459,7 @@
         int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
 
         /* ChachaPoly has fixed length nonce and MAC (tag) */
-        if ((iv_len != ctx->cipher_info->iv_size) ||
+        if ((iv_len != mbedtls_cipher_info_get_iv_size(ctx->cipher_info)) ||
             (tag_len != 16U)) {
             return MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA;
         }
diff --git a/library/pkcs12.c b/library/pkcs12.c
index a0966f6..8540de2 100644
--- a/library/pkcs12.c
+++ b/library/pkcs12.c
@@ -155,7 +155,7 @@
 
     if ((ret = pkcs12_pbe_derive_key_iv(pbe_params, md_type, pwd, pwdlen,
                                         key, keylen,
-                                        iv, cipher_info->iv_size)) != 0) {
+                                        iv, mbedtls_cipher_info_get_iv_size(cipher_info))) != 0) {
         return ret;
     }
 
@@ -171,7 +171,7 @@
         goto exit;
     }
 
-    if ((ret = mbedtls_cipher_set_iv(&cipher_ctx, iv, cipher_info->iv_size)) != 0) {
+    if ((ret = mbedtls_cipher_set_iv(&cipher_ctx, iv, mbedtls_cipher_info_get_iv_size(cipher_info))) != 0) {
         goto exit;
     }
 
diff --git a/library/pkcs5.c b/library/pkcs5.c
index 6cbb520..8d39eab 100644
--- a/library/pkcs5.c
+++ b/library/pkcs5.c
@@ -179,7 +179,7 @@
     keylen = mbedtls_cipher_info_get_key_bitlen(cipher_info) / 8;
 
     if (enc_scheme_params.tag != MBEDTLS_ASN1_OCTET_STRING ||
-        enc_scheme_params.len != cipher_info->iv_size) {
+        enc_scheme_params.len != mbedtls_cipher_info_get_iv_size(cipher_info)) {
         return MBEDTLS_ERR_PKCS5_INVALID_FORMAT;
     }
 
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index f0067f4..36c96f2 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -8420,7 +8420,7 @@
 #if defined(MBEDTLS_USE_PSA_CRYPTO)
         transform->ivlen = PSA_CIPHER_IV_LENGTH(key_type, alg);
 #else
-        transform->ivlen = cipher_info->iv_size;
+        transform->ivlen = mbedtls_cipher_info_get_iv_size(cipher_info);
 #endif /* MBEDTLS_USE_PSA_CRYPTO */
 
         /* Minimum length */