asn1: fix out-of-bounds read in decoding constructed objects

* OpenSSL::ASN1.{decode,decode_all,traverse}: have a bug of
  out-of-bounds read. int_ossl_asn1_decode0_cons() does not give the
  correct available length to ossl_asn1_decode() when decoding the
  inner components of a constructed object. This can cause
  out-of-bounds read if a crafted input given.

Reference: https://hackerone.com/reports/170316
https://github.com/ruby/openssl/commit/1648afef33c1d97fb203c82291b8a61269e85d3b



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_3@59800 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 23 insertions, 0 deletions

diff --git a/test/openssl/test_asn1.rb b/test/openssl/test_asn1.rb
index fd2118d808..109fd95fd4 100644
--- a/test/openssl/test_asn1.rb
+++ b/test/openssl/test_asn1.rb
@@ -596,6 +596,29 @@ rEzBQ0F9dUyqQ9gyRg8KHhDfv9HzT1d/rnUZMkoombwYBRIUChGCYV0GnJcan2Zm
     assert_equal(false, asn1.value[3].infinite_length)
   end
 
+  def test_decode_constructed_overread
+    test = %w{ 31 06 31 02 30 02 05 00 }
+    #                          ^ <- invalid
+    raw = [test.join].pack("H*")
+    ret = []
+    assert_raise(OpenSSL::ASN1::ASN1Error) {
+      OpenSSL::ASN1.traverse(raw) { |x| ret << x }
+    }
+    assert_equal 2, ret.size
+    assert_equal 17, ret[0][6]
+    assert_equal 17, ret[1][6]
+
+    test = %w{ 31 80 30 03 00 00 }
+    #                    ^ <- invalid
+    raw = [test.join].pack("H*")
+    ret = []
+    assert_raise(OpenSSL::ASN1::ASN1Error) {
+      OpenSSL::ASN1.traverse(raw) { |x| ret << x }
+    }
+    assert_equal 1, ret.size
+    assert_equal 17, ret[0][6]
+  end
+
   private
 
   def assert_universal(tag, asn1)