File openssl-CVE-2021-23840.patch of Package openssl.20898

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File openssl-CVE-2021-23840.patch of Package openssl.20898

From 6a51b9e1d0cf0bf8515f7201b68fb0a3482b3dc1 Mon Sep 17 00:00:00 2001
From: Matt Caswell <matt@openssl.org>
Date: Tue, 2 Feb 2021 17:17:23 +0000
Subject: [PATCH] Don't overflow the output length in EVP_CipherUpdate calls

CVE-2021-23840

Reviewed-by: Paul Dale <pauli@openssl.org>
---
 crypto/err/openssl.txt   |  3 ++-
 crypto/evp/evp_enc.c     | 27 +++++++++++++++++++++++++++
 crypto/evp/evp_err.c     |  4 +++-
 include/openssl/evperr.h |  7 +++----
 4 files changed, 35 insertions(+), 6 deletions(-)

Index: openssl-1.0.2j/crypto/evp/evp_enc.c
===================================================================
--- openssl-1.0.2j.orig/crypto/evp/evp_enc.c
+++ openssl-1.0.2j/crypto/evp/evp_enc.c
@@ -57,6 +57,7 @@
  */
 
 #include <stdio.h>
+#include <limits.h>
 #include "cryptlib.h"
 #include <openssl/evp.h>
 #include <openssl/err.h>
@@ -417,6 +418,19 @@ 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 +532,19 @@ 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_EncryptUpdate 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;
Index: openssl-1.0.2j/crypto/evp/evp_err.c
===================================================================
--- openssl-1.0.2j.orig/crypto/evp/evp_err.c
+++ openssl-1.0.2j/crypto/evp/evp_err.c
@@ -92,7 +92,9 @@ static ERR_STRING_DATA EVP_str_functs[]
     {ERR_FUNC(EVP_F_EVP_CIPHER_CTX_SET_KEY_LENGTH),
      "EVP_CIPHER_CTX_set_key_length"},
     {ERR_FUNC(EVP_F_EVP_DECRYPTFINAL_EX), "EVP_DecryptFinal_ex"},
+    {ERR_FUNC(EVP_F_EVP_DECRYPTUPDATE), "EVP_DecryptUpdate"},
     {ERR_FUNC(EVP_F_EVP_DIGESTINIT_EX), "EVP_DigestInit_ex"},
+    {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"},
@@ -212,6 +214,7 @@ 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"},
Index: openssl-1.0.2j/crypto/evp/evp.h
===================================================================
--- openssl-1.0.2j.orig/crypto/evp/evp.h
+++ openssl-1.0.2j/crypto/evp/evp.h
@@ -1427,7 +1427,9 @@ void ERR_load_EVP_strings(void);
 # define EVP_F_EVP_CIPHER_CTX_CTRL                        124
 # define EVP_F_EVP_CIPHER_CTX_SET_KEY_LENGTH              122
 # define EVP_F_EVP_DECRYPTFINAL_EX                        101
+# define EVP_F_EVP_DECRYPTUPDATE                          166
 # define EVP_F_EVP_DIGESTINIT_EX                          128
+# define EVP_F_EVP_ENCRYPTUPDATE                          167
 # define EVP_F_EVP_ENCRYPTFINAL_EX                        127
 # define EVP_F_EVP_MD_CTX_COPY_EX                         110
 # define EVP_F_EVP_MD_SIZE                                162
@@ -1537,6 +1539,7 @@ 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

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