File openssl-CVE-2021-23840.patch of Package openssl-1_1

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File openssl-CVE-2021-23840.patch of Package openssl-1_1 (Revision 3d3c7a179ef13275c1cd00bb59468648)

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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-1.1.0i/crypto/evp/evp_enc.c
===================================================================
--- openssl-1.1.0i.orig/crypto/evp/evp_enc.c
+++ openssl-1.1.0i/crypto/evp/evp_enc.c
@@ -8,6 +8,7 @@
  */
 
 #include <stdio.h>
+#include <limits.h>
 #include <assert.h>
 #include "internal/cryptlib.h"
 #include <openssl/evp.h>
@@ -379,6 +380,19 @@ 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);
             inl -= j;
             in += j;
@@ -495,6 +509,19 @@ int EVP_DecryptUpdate(EVP_CIPHER_CTX *ct
             EVPerr(EVP_F_EVP_DECRYPTUPDATE, EVP_R_PARTIALLY_OVERLAPPING);
             return 0;
         }
+        /*
+         * 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;
Index: openssl-1.1.0i/crypto/evp/evp_err.c
===================================================================
--- openssl-1.1.0i.orig/crypto/evp/evp_err.c
+++ openssl-1.1.0i/crypto/evp/evp_err.c
@@ -150,6 +151,7 @@ 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_PARAMETER_TOO_LARGE), "parameter too large"},
     {ERR_REASON(EVP_R_PARTIALLY_OVERLAPPING),
      "partially overlapping buffers"},
Index: openssl-1.1.0i/include/openssl/evp.h
===================================================================
--- openssl-1.1.0i.orig/include/openssl/evp.h
+++ openssl-1.1.0i/include/openssl/evp.h
@@ -1579,6 +1580,7 @@ int ERR_load_EVP_strings(void);
 # define EVP_R_NO_OPERATION_SET                           149
 # 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_PARAMETER_TOO_LARGE                        187
 # define EVP_R_PARTIALLY_OVERLAPPING                      162
 # define EVP_R_PBKDF2_ERROR                               176

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