nahi	2011-07-28 22:48:05 +0900 (Thu, 28 Jul 2011)

  New Revision: 32723

  http://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=rev&revision=32723

  Log:
    * ext/openssl/ossl_cipher.c (ossl_cipher_initialize): Avoid possible
      SEGV from AES encryption/decryption. Processing data by
      Cipher#update without initializing key (meaningless usage of Cipher
      object since we don't offer a way to export a key) could cause SEGV.
    
      In OpenSSL, the EVP which has EVP_CIPH_RAND_KEY flag (such as DES3) 
      allows uninitialized key, but other EVPs (such as AES) does not
      allow it. Calling EVP_CipherUpdate() without initializing key causes
      SEGV so we set the data filled with "\0" as the key by default. See
      #2768.
    
    * test/openssl/test_cipher.rb: test it.

  Modified files:
    trunk/ChangeLog
    trunk/ext/openssl/ossl_cipher.c
    trunk/test/openssl/test_cipher.rb

Index: ChangeLog
===================================================================
--- ChangeLog	(revision 32722)
+++ ChangeLog	(revision 32723)
@@ -1,3 +1,18 @@
+Thu Jul 28 22:36:06 2011  Hiroshi Nakamura  <nahi@r...>
+
+	* ext/openssl/ossl_cipher.c (ossl_cipher_initialize): Avoid possible
+	  SEGV from AES encryption/decryption. Processing data by
+	  Cipher#update without initializing key (meaningless usage of Cipher
+	  object since we don't offer a way to export a key) could cause SEGV.
+	  
+	  In OpenSSL, the EVP which has EVP_CIPH_RAND_KEY flag (such as DES3)
+	  allows uninitialized key, but other EVPs (such as AES) does not
+	  allow it. Calling EVP_CipherUpdate() without initializing key causes
+	  SEGV so we set the data filled with "\0" as the key by default. See
+	  #2768.
+
+	* test/openssl/test_cipher.rb: test it.
+
 Thu Jul 28 14:25:08 2011  NAKAMURA Usaku  <usa@r...>
 
 	* lib/rubygems/user_interaction.rb (Gem::StreamUI#tty?): typo.
Index: ext/openssl/ossl_cipher.c
===================================================================
--- ext/openssl/ossl_cipher.c	(revision 32722)
+++ ext/openssl/ossl_cipher.c	(revision 32723)
@@ -102,6 +102,7 @@
     EVP_CIPHER_CTX *ctx;
     const EVP_CIPHER *cipher;
     char *name;
+    unsigned char key[EVP_MAX_KEY_LENGTH];
 
     name = StringValuePtr(str);
     GetCipherInit(self, ctx);
@@ -113,7 +114,14 @@
     if (!(cipher = EVP_get_cipherbyname(name))) {
 	ossl_raise(rb_eRuntimeError, "unsupported cipher algorithm (%s)", name);
     }
-    if (EVP_CipherInit_ex(ctx, cipher, NULL, NULL, NULL, -1) != 1)
+    /*
+     * The EVP which has EVP_CIPH_RAND_KEY flag (such as DES3) allows
+     * uninitialized key, but other EVPs (such as AES) does not allow it.
+     * Calling EVP_CipherUpdate() without initializing key causes SEGV so we
+     * set the data filled with "\0" as the key by default.
+     */
+    memset(key, 0, EVP_MAX_KEY_LENGTH);
+    if (EVP_CipherInit_ex(ctx, cipher, NULL, key, NULL, -1) != 1)
 	ossl_raise(eCipherError, NULL);
 
     return self;
Index: test/openssl/test_cipher.rb
===================================================================
--- test/openssl/test_cipher.rb	(revision 32722)
+++ test/openssl/test_cipher.rb	(revision 32723)
@@ -90,6 +90,15 @@
         assert_equal(pt, c2.update(ct) + c2.final)
       }
     end
+
+    def test_AES_crush
+      500.times do
+        assert_nothing_raised("[Bug #2768]") do
+          # it caused OpenSSL SEGV by uninitialized key
+          OpenSSL::Cipher::AES128.new("ECB").update "." * 17
+        end
+      end
+    end
   end
 end
 

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