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LibTLS: Don't attempt to read past EOF when parsing TBSCertificate

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This allows the decoder to fail gracefully when reading a partial or
malformed TBSCertificate. We also now ensure that the certificate data
is valid before making a copy of it.
This commit is contained in:
Tim Ledbetter 2023-10-05 17:51:29 +01:00 • committed by Andreas Kling
parent 65b50ecc1a
commit e6d9bb0774
4 changed files with 21 additions and 2 deletions
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6
Userland/Libraries/LibTLS/Certificate.cpp
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@ -691,10 +691,11 @@ static ErrorOr<Certificate> parse_tbs_certificate(Crypto::ASN1::Decoder& decoder
ENTER_TYPED_SCOPE(Sequence, "TBSCertificate"sv);
auto post_cert_buffer = TRY(decoder.peek_entry_bytes());
auto asn1_data = TRY(ByteBuffer::copy(pre_cert_buffer.slice(0, post_cert_buffer.size() + entry_length_byte_count)));
if (pre_cert_buffer.size() < post_cert_buffer.size() + entry_length_byte_count) {
ERROR_WITH_SCOPE("Unexpected end of file");
}
Certificate certificate;
certificate.tbs_asn1 = asn1_data;
certificate.version = TRY(parse_certificate_version(decoder, current_scope)).to_u64();
certificate.serial_number = TRY(parse_serial_number(decoder, current_scope));
certificate.algorithm = TRY(parse_algorithm_identifier(decoder, current_scope));
@ -702,6 +703,7 @@ static ErrorOr<Certificate> parse_tbs_certificate(Crypto::ASN1::Decoder& decoder
certificate.validity = TRY(parse_validity(decoder, current_scope));
certificate.subject = TRY(parse_name(decoder, current_scope));
certificate.public_key = TRY(parse_subject_public_key_info(decoder, current_scope));
certificate.tbs_asn1 = TRY(ByteBuffer::copy(pre_cert_buffer.slice(0, post_cert_buffer.size() + entry_length_byte_count)));
if (!decoder.eof()) {
auto tag = TRY(decoder.peek());