diff -up openssl-1.0.2k/crypto/evp/evp_enc.c.int-overflow openssl-1.0.2k/crypto/evp/evp_enc.c
--- openssl-1.0.2k/crypto/evp/evp_enc.c.int-overflow	2021-09-01 14:17:32.813927827 +0200
+++ openssl-1.0.2k/crypto/evp/evp_enc.c	2021-09-01 14:17:32.909929103 +0200
@@ -57,6 +57,7 @@
  */
 
 #include <stdio.h>
+#include <limits.h>
 #include "cryptlib.h"
 #include <openssl/evp.h>
 #include <openssl/err.h>
@@ -417,6 +418,18 @@ int EVP_EncryptUpdate(EVP_CIPHER_CTX *ct
             return 1;
         } else {
             j = bl - i;
+            /*
+             * Once we've processed the first j bytes from in, the amount of
+             * data left that is a multiple of the block length is:
+             * (inl - j) & ~(bl - 1)
+             * We must ensure that this amount of data, plus the one block that
+             * we process from ctx->buf does not exceed INT_MAX
+             */
+            if (((inl - j) & ~(bl - 1)) > INT_MAX - bl) {
+                EVPerr(EVP_F_EVP_ENCRYPTUPDATE,
+                       EVP_R_OUTPUT_WOULD_OVERFLOW);
+                return 0;
+            } 
             memcpy(&(ctx->buf[i]), in, j);
             if (!M_do_cipher(ctx, out, ctx->buf, bl))
                 return 0;
@@ -518,6 +531,19 @@ int EVP_DecryptUpdate(EVP_CIPHER_CTX *ct
     OPENSSL_assert(b <= sizeof ctx->final);
 
     if (ctx->final_used) {
+        /*
+         * final_used is only ever set if buf_len is 0. Therefore the maximum
+         * length output we will ever see from evp_EncryptDecryptUpdate is
+         * the maximum multiple of the block length that is <= inl, or just:
+         * inl & ~(b - 1)
+         * Since final_used has been set then the final output length is:
+         * (inl & ~(b - 1)) + b
+         * This must never exceed INT_MAX
+         */
+        if ((inl & ~(b - 1)) > INT_MAX - b) {
+            EVPerr(EVP_F_EVP_DECRYPTUPDATE, EVP_R_OUTPUT_WOULD_OVERFLOW);
+            return 0;
+        }
         memcpy(out, ctx->final, b);
         out += b;
         fix_len = 1;
diff -up openssl-1.0.2k/crypto/evp/evp_err.c.int-overflow openssl-1.0.2k/crypto/evp/evp_err.c
--- openssl-1.0.2k/crypto/evp/evp_err.c.int-overflow	2017-01-26 14:22:03.000000000 +0100
+++ openssl-1.0.2k/crypto/evp/evp_err.c	2021-09-01 14:17:32.909929103 +0200
@@ -1,6 +1,6 @@
 /* crypto/evp/evp_err.c */
 /* ====================================================================
- * Copyright (c) 1999-2016 The OpenSSL Project.  All rights reserved.
+ * Copyright (c) 1999-2021 The OpenSSL Project.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -93,6 +93,8 @@ static ERR_STRING_DATA EVP_str_functs[]
      "EVP_CIPHER_CTX_set_key_length"},
     {ERR_FUNC(EVP_F_EVP_DECRYPTFINAL_EX), "EVP_DecryptFinal_ex"},
     {ERR_FUNC(EVP_F_EVP_DIGESTINIT_EX), "EVP_DigestInit_ex"},
+    {ERR_FUNC(EVP_F_EVP_DECRYPTUPDATE), "EVP_DecryptUpdate"},
+    {ERR_FUNC(EVP_F_EVP_ENCRYPTUPDATE), "EVP_EncryptUpdate"},
     {ERR_FUNC(EVP_F_EVP_ENCRYPTFINAL_EX), "EVP_EncryptFinal_ex"},
     {ERR_FUNC(EVP_F_EVP_MD_CTX_COPY_EX), "EVP_MD_CTX_copy_ex"},
     {ERR_FUNC(EVP_F_EVP_MD_SIZE), "EVP_MD_size"},
@@ -213,6 +215,8 @@ static ERR_STRING_DATA EVP_str_reasons[]
     {ERR_REASON(EVP_R_OPERATION_NOT_SUPPORTED_FOR_THIS_KEYTYPE),
      "operation not supported for this keytype"},
     {ERR_REASON(EVP_R_OPERATON_NOT_INITIALIZED), "operaton not initialized"},
+    {ERR_REASON(EVP_R_OUTPUT_WOULD_OVERFLOW),
+    "output would overflow"},
     {ERR_REASON(EVP_R_PKCS8_UNKNOWN_BROKEN_TYPE),
      "pkcs8 unknown broken type"},
     {ERR_REASON(EVP_R_PRIVATE_KEY_DECODE_ERROR), "private key decode error"},
diff -up openssl-1.0.2k/crypto/evp/evp.h.int-overflow openssl-1.0.2k/crypto/evp/evp.h
--- openssl-1.0.2k/crypto/evp/evp.h.int-overflow	2021-09-01 14:17:32.871928598 +0200
+++ openssl-1.0.2k/crypto/evp/evp.h	2021-09-01 14:24:37.803577096 +0200
@@ -1,5 +1,5 @@
 /* crypto/evp/evp.h */
-/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
+/* Copyright (C) 1995-2021 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
  * This package is an SSL implementation written
@@ -1404,6 +1404,8 @@ void ERR_load_EVP_strings(void);
 # define EVP_F_EVP_CIPHER_CTX_SET_KEY_LENGTH              122
 # define EVP_F_EVP_DECRYPTFINAL_EX                        101
 # define EVP_F_EVP_DIGESTINIT_EX                          128
+# define EVP_F_EVP_DECRYPTUPDATE                          180
+# define EVP_F_EVP_ENCRYPTUPDATE                          181
 # define EVP_F_EVP_ENCRYPTFINAL_EX                        127
 # define EVP_F_EVP_MD_CTX_COPY_EX                         110
 # define EVP_F_EVP_MD_SIZE                                162
@@ -1514,6 +1516,7 @@ void ERR_load_EVP_strings(void);
 # define EVP_R_NO_VERIFY_FUNCTION_CONFIGURED              105
 # define EVP_R_OPERATION_NOT_SUPPORTED_FOR_THIS_KEYTYPE   150
 # define EVP_R_OPERATON_NOT_INITIALIZED                   151
+# define EVP_R_OUTPUT_WOULD_OVERFLOW                      184
 # define EVP_R_PKCS8_UNKNOWN_BROKEN_TYPE                  117
 # define EVP_R_PRIVATE_KEY_DECODE_ERROR                   145
 # define EVP_R_PRIVATE_KEY_ENCODE_ERROR                   146