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Bug #4233
closedssl : Integer underflow in ssl parsing SSLV3_HANDSHAKE_PROTOCOL
Affected Versions:
Effort:
Difficulty:
Label:
Needs backport to 5.0, Needs backport to 6.0
Description
Found by oss-fuzz
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=28399
First we being parsing SSLV3_HANDSHAKE_PROTOCOL
We set message_start, bytes_processed and message_length in SSLv3ParseHandshakeProtocol
Then, we break out of this SSLV3_HANDSHAKE_PROTOCOL parsing because the other side of the connexion set SSL_AL_FLAG_CHANGE_CIPHER_SPEC
This leads to increasing bytes_processed at the end of SSLv3Decode
Then, we do not break anymore out of this SSLV3_HANDSHAKE_PROTOCOL parsing because the other side set SSL_AL_FLAG_STATE_CLIENT_HELLO
And bytes_processed is now over message_start + message_length
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