Base64 data issue/v8 #9160
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Base64 data issue/v8 #9160
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RFC 2045 states that any invalid character should be skipped over, this is the RFC used by mime handler in Suricata code to deal with base64 encoded data. So far, only spaces were skipped as a part of implementation of this RFC, extend it to also skip over any other invalid character. Add corresponding test.
Padding bytes for the last remainder data should be as follows: Case | Remainder bytes | Padding ---------------------------------------------- I | 1 | 3 II | 2 | 2 III | 3 | 1 However, we calculate the decoded_bytes with the formula: decoded_bytes = ASCII_BLOCK - padding this means for Case I when padding is 3 bytes, the decoded_bytes would be 0. This is incorrect for any trailing data. In any of the above cases, if the parsing was successful, there should at least be 1 decoded byte.
Just like the check for destination buffer size done previously for complete data, it should also be done for the trailing data to avoid goind out of bounds.
The destination buffer should be able to hold at least 3 Bytes during the processing of the last block of data. If it cannot hold at least 3 Bytes, then that may lead to dynamic buffer overflow while decoding.
victorjulien
reviewed
Jul 6, 2023
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WARNING:
Pipeline 15021 |
scan-build warning ^ |
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SV PR needs rebase? |
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Link to redmine ticket: https://redmine.openinfosecfoundation.org/issues/6135
SV_BRANCH=OISF/suricata-verify#1292
Previous PR: #9159
Changes since v7: