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Fix OOB write in fillExtraMM nonce handling #36

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Merged
MoneroOcean merged 1 commit into from
Jun 3, 2026
Merged

Fix OOB write in fillExtraMM nonce handling #36

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16 changes: 11 additions & 5 deletions src/main.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -108,16 +108,22 @@ static bool fillExtraMM(cryptonote::block& block1, const cryptonote::block& bloc
return false;
}

const int extra_nonce_size = extra[pos + 1];
const int new_extra_nonce_size = extra_nonce_size - MM_NONCE_SIZE;
const size_t extra_nonce_size = extra[pos + 1];
const size_t extra_nonce_start = pos + 2;
if (extra_nonce_start > extra.size() || extra_nonce_start + extra_nonce_size > extra.size()) {
fprintf(stderr, "Malformed TX_EXTRA_NONCE length in extra\n");
return false;
}

if (new_extra_nonce_size < 0) {
if (extra_nonce_size < MM_NONCE_SIZE) {
fprintf(stderr, "Too small extra size, can't fit MM tag here\n");
return false;
}

extra[pos + 1] = new_extra_nonce_size;
std::copy(extra_nonce_replace.begin(), extra_nonce_replace.end(), extra.begin() + pos + 1 + new_extra_nonce_size + 1);
const size_t new_extra_nonce_size = extra_nonce_size - MM_NONCE_SIZE;

extra[pos + 1] = static_cast<uint8_t>(new_extra_nonce_size);
std::copy(extra_nonce_replace.begin(), extra_nonce_replace.end(), extra.begin() + extra_nonce_start + new_extra_nonce_size);
//extra.resize(pos + 1 + extra_nonce_size + 1);

// get the most recent timestamp (solve duplicated timestamps on child coin)
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