https://clickhouse-test-reports.s3.yandex.net/13925/0f492917338ba5b20728563e38abc35be67d606c/stress_test_(memory)/stderr.log

MemorySanitizer: use-of-uninitialized-value in DB::FunctionToStringCutToZero::tryExecuteString.
Uninitialized value was created ... in DB::FunctionBase64ConversionDB::Base64Decode::executeImpl
(from ExecuteScalarSubqueriesVisitor -> ... -> InterpreterSelectQuery::getSampleBlockImpl() -> ... -> IFunction::executeImplDryRun())

There's only one query with `toStringCutToZero(base64Decode)` in server log

```
SELECT JSONExtractKeysAndValues(-0, (CAST((( SELECT ['"O'], (CAST((( SELECT toStringCutToZero((CAST((base64Decode('UE')) AS String))) ) AS op, ( SELECT positionCaseInsensitiveUTF8() ) AS uxxgbn) AS String)), (CAST((-44955.4) AS Date)), regionToDistrict(NULL) ) AS q) AS DateTime)))
```
}
            else
            {
                if (srclen > 0)
                {
                    
                    
                    auto savepoint = dst_pos;
                    outlen = _tb64d(reinterpret_cast<const uint8_t *>(source), srclen, reinterpret_cast<uint8_t *>(dst_pos));
                    if (!outlen)
                    {
                        outlen = 0;
                        dst_pos = savepoint;
                        
                        dst_pos[0] = 0;
                    }
                }
            }
            source += srclen + 1;
            dst_pos += outlen + 1;
            dst_offsets[row] = dst_pos - dst;
            src_offset_prev = src_offsets[row];
        }
        dst_data.resize(dst_pos - dst);
        block.getByPosition(result).column = std::move(dst_column);
    }
};
}
#endif