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asn1: limit nesting depth in OpenSSL::ASN1.decode #1060

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asn1: limit nesting depth in OpenSSL::ASN1.decode #1060

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6 changes: 6 additions & 0 deletions ext/openssl/ossl_asn1.c
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Original file line number Diff line number Diff line change
Expand Up @@ -889,6 +889,8 @@ int_ossl_asn1_decode0_cons(unsigned char **pp, long max_len, long length,
return asn1data;
}

#define MAX_NESTING_DEPTH 200

static VALUE
ossl_asn1_decode0(unsigned char **pp, long length, long *offset, int depth,
int yield, long *num_read)
Expand All @@ -899,6 +901,10 @@ ossl_asn1_decode0(unsigned char **pp, long length, long *offset, int depth,
int tag, tc, j;
VALUE asn1data, tag_class;

if (depth > MAX_NESTING_DEPTH) {
ossl_raise(eASN1Error, "nesting depth %d exceeds limit", depth);
}

p = *pp;
start = p;
p0 = p;
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14 changes: 14 additions & 0 deletions test/openssl/test_asn1.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -696,6 +696,20 @@ def test_decode_constructed_overread
assert_equal 17, ret[0][6]
end

def test_decode_constructed_deeply_nested
bool = OpenSSL::ASN1::Boolean.new(true)
nested_100 = B(%w{ 30 80 }) * 100 + bool.to_der + B(%w{ 00 00 }) * 100
decoded = OpenSSL::ASN1.decode(nested_100)
assert_equal(nested_100, decoded.to_der)
content = 100.times.inject(decoded) { |a,| a.value[0] }
assert_kind_of(OpenSSL::ASN1::Boolean, content)

nested_500 = B(%w{ 30 80 }) * 500 + bool.to_der + B(%w{ 00 00 }) * 500
assert_raise_with_message(OpenSSL::ASN1::ASN1Error, /nesting depth/) {
OpenSSL::ASN1.decode(nested_500)
}
end

def test_constructive_each
data = [OpenSSL::ASN1::Integer.new(0), OpenSSL::ASN1::Integer.new(1)]
seq = OpenSSL::ASN1::Sequence.new data
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