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Fix undefined behaviour in visual server as reported by ubsan/asan. #51266

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Fix undefined behaviour in visual server as reported by ubsan/asan. #51266

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6 changes: 4 additions & 2 deletions servers/visual_server.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1429,8 +1429,10 @@ Array VisualServer::_get_array_from_surface(uint32_t p_format, PoolVector<uint8_
PoolVector<Vector3>::Write w = arr_3d.write();

for (int j = 0; j < p_vertex_len; j++) {
const float *v = (const float *)&r[j * total_elem_size + offsets[i]];
w[j] = Vector3(v[0], v[1], v[2]);
const float &x = r[j * total_elem_size + offsets[i]];
const float &y = r[j * total_elem_size + offsets[i] + 1];
const float &z = r[j * total_elem_size + offsets[i] + 2];
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@lawnjelly lawnjelly Aug 5, 2021 •
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Is this correct given that r seems to be 8 bit?

PoolVector<uint8_t>::Read r = p_vertex_data.read();

Use brackets for precedence to make it clear, but I think this does e.g.

const float &y = r[(j * total_elem_size) + offsets[i] + 1];

The +1 is 1 byte, therefore unaligned.

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@jordo jordo Aug 11, 2021 •
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This fix doesn't seem correct? Since r is a byte buffer, wouldn't you want to index?

const float &y = r[j * total_elem_size + offsets[i] + 4]
const float &z = r[j * total_elem_size + offsets[i] + 8]

w[j] = Vector3(x, y, z);
}
}

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