From 1648afef33c1d97fb203c82291b8a61269e85d3b Mon Sep 17 00:00:00 2001 From: Kazuki Yamaguchi Date: Mon, 19 Sep 2016 15:38:44 +0900 Subject: [PATCH] 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 Upstream-Status: Backport CVE: CVE-2017-14033 Signed-off-by: Rajkumar Veer --- ext/openssl/ossl_asn1.c | 13 ++++++------- test/test_asn1.rb | 23 +++++++++++++++++++++++ 2 files changed, 29 insertions(+), 7 deletions(-) --- a/ext/openssl/ossl_asn1.c +++ b/ext/openssl/ossl_asn1.c @@ -871,19 +871,18 @@ { VALUE value, asn1data, ary; int infinite; - long off = *offset; + long available_len, off = *offset; infinite = (j == 0x21); ary = rb_ary_new(); - while (length > 0 || infinite) { + available_len = infinite ? max_len : length; + while (available_len > 0 ) { long inner_read = 0; - value = ossl_asn1_decode0(pp, max_len, &off, depth + 1, yield, &inner_read); + value = ossl_asn1_decode0(pp, available_len, &off, depth + 1, yield, &inner_read); *num_read += inner_read; - max_len -= inner_read; + available_len -= inner_read; rb_ary_push(ary, value); - if (length > 0) - length -= inner_read; if (infinite && NUM2INT(ossl_asn1_get_tag(value)) == V_ASN1_EOC && @@ -974,7 +973,7 @@ if(j & V_ASN1_CONSTRUCTED) { *pp += hlen; off += hlen; - asn1data = int_ossl_asn1_decode0_cons(pp, length, len, &off, depth, yield, j, tag, tag_class, &inner_read); + asn1data = int_ossl_asn1_decode0_cons(pp, length - hlen, len, &off, depth, yield, j, tag, tag_class, &inner_read); inner_read += hlen; } else { --- a/test/openssl/test_asn1.rb +++ b/test/openssl/test_asn1.rb @@ -595,6 +595,29 @@ 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)