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fix(advert): validate parser input lengths before decoding fields #1816

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fix(advert): validate parser input lengths before decoding fields #1816

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13 changes: 11 additions & 2 deletions src/helpers/AdvertDataHelpers.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -29,19 +29,25 @@
AdvertDataParser::AdvertDataParser(const uint8_t app_data[], uint8_t app_data_len) {
_name[0] = 0;
_lat = _lon = 0;
_flags = app_data[0];
_flags = 0;
_valid = false;
_extra1 = _extra2 = 0;
if (app_data == NULL || app_data_len == 0) return;

_flags = app_data[0];

int i = 1;
if (_flags & ADV_LATLON_MASK) {
if (i + 8 > app_data_len) return;
memcpy(&_lat, &app_data[i], 4); i += 4;
memcpy(&_lon, &app_data[i], 4); i += 4;
}
if (_flags & ADV_FEAT1_MASK) {
if (i + 2 > app_data_len) return;
memcpy(&_extra1, &app_data[i], 2); i += 2;
}
if (_flags & ADV_FEAT2_MASK) {
if (i + 2 > app_data_len) return;
memcpy(&_extra2, &app_data[i], 2); i += 2;
}

Expand All @@ -51,6 +57,9 @@
nlen = app_data_len - i; // remainder of app_data
}
if (nlen > 0) {
if (nlen > MAX_ADVERT_DATA_SIZE - 1) {
nlen = MAX_ADVERT_DATA_SIZE - 1;
}
memcpy(_name, &app_data[i], nlen);
_name[nlen] = 0; // set null terminator
}
Expand Down Expand Up @@ -84,4 +93,4 @@ void AdvertTimeHelper::formatRelativeTimeDiff(char dest[], int32_t seconds_from_
}
}
}
}
}