Fix partial block encryption in cfb and ofb for s390x (legacy)

Use the number of processed bytes information (num) from the generic
cipher context for the partial block handling in cfb and ofb also in
s390x-legacy code. For more details see 4df92c1 ("Fix partial block
encryption in cfb and ofb for s390x").

Signed-off-by: Holger Dengler <dengler@linux.ibm.com>

Reviewed-by: Shane Lontis <shane.lontis@oracle.com>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from #23201)

(cherry picked from commit f9ccd20)

crypto/evp/e_aes.c

@@ -831,8 +831,6 @@ typedef struct {
         /* KMO-AES parameter block - end */
     } kmo;
     unsigned int fc;
-
-    int res;
 } S390X_AES_OFB_CTX;
 
 typedef struct {
@@ -849,8 +847,6 @@ typedef struct {
         /* KMF-AES parameter block - end */
     } kmf;
     unsigned int fc;
-
-    int res;
 } S390X_AES_CFB_CTX;
 
 typedef struct {
@@ -1002,7 +998,6 @@ static int s390x_aes_ofb_init_key(EVP_CIPHER_CTX *ctx,
     memcpy(cctx->kmo.param.cv, iv, ivlen);
     memcpy(cctx->kmo.param.k, key, keylen);
     cctx->fc = S390X_AES_FC(keylen);
-    cctx->res = 0;
     return 1;
 }
 
@@ -1012,7 +1007,7 @@ static int s390x_aes_ofb_cipher(EVP_CIPHER_CTX *ctx, unsigned char *out,
     S390X_AES_OFB_CTX *cctx = EVP_C_DATA(S390X_AES_OFB_CTX, ctx);
     const int ivlen = EVP_CIPHER_CTX_get_iv_length(ctx);
     unsigned char *iv = EVP_CIPHER_CTX_iv_noconst(ctx);
-    int n = cctx->res;
+    int n = ctx->num;
     int rem;
 
     memcpy(cctx->kmo.param.cv, iv, ivlen);
@@ -1045,7 +1040,7 @@ static int s390x_aes_ofb_cipher(EVP_CIPHER_CTX *ctx, unsigned char *out,
     }
 
     memcpy(iv, cctx->kmo.param.cv, ivlen);
-    cctx->res = n;
+    ctx->num = n;
     return 1;
 }
 
@@ -1063,7 +1058,6 @@ static int s390x_aes_cfb_init_key(EVP_CIPHER_CTX *ctx,
     if (!enc)
         cctx->fc |= S390X_DECRYPT;
 
-    cctx->res = 0;
     memcpy(cctx->kmf.param.cv, iv, ivlen);
     memcpy(cctx->kmf.param.k, key, keylen);
     return 1;
@@ -1077,7 +1071,7 @@ static int s390x_aes_cfb_cipher(EVP_CIPHER_CTX *ctx, unsigned char *out,
     const int enc = EVP_CIPHER_CTX_is_encrypting(ctx);
     const int ivlen = EVP_CIPHER_CTX_get_iv_length(ctx);
     unsigned char *iv = EVP_CIPHER_CTX_iv_noconst(ctx);
-    int n = cctx->res;
+    int n = ctx->num;
     int rem;
     unsigned char tmp;
 
@@ -1115,7 +1109,7 @@ static int s390x_aes_cfb_cipher(EVP_CIPHER_CTX *ctx, unsigned char *out,
     }
 
     memcpy(iv, cctx->kmf.param.cv, ivlen);
-    cctx->res = n;
+    ctx->num = n;
     return 1;
 }