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fix(advert): bounds-check optional fields before memcpy #2531

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fix(advert): bounds-check optional fields before memcpy #2531

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9 changes: 8 additions & 1 deletion src/helpers/AdvertDataHelpers.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -32,16 +32,23 @@
_flags = app_data[0];
_valid = false;
_extra1 = _extra2 = 0;

int i = 1;
// Bounds-check each optional field BEFORE memcpy: a crafted advert with all
// FLAG_* bits set but app_data_len=1 would otherwise over-read up to 12 bytes
// past the buffer (the trailing app_data_len >= i check below only catches it
// after the fact). Returning early leaves _valid=false.
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;
}

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