Fix buffer zeroing with offset in map_buffer #2916
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The tracked uninitialized ranges are relative to the start of the buffer, however when mapping the buffer at an offset the resulting pointer is not the start of the buffer, and therefore the offset has to be taken into account.
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Checklist
cargo clippy.Connections
None.
Description
The buffer zeroing code in
map_buffercurrently writes out of bounds if a non zero offset is passed.This is because the map_buffer code passes the
mapped_pointer + uninitialized.starttowrite_bytes, however the uninitialized range is relative to the start of the buffer while our mapped pointer is offset.The offset parameter has to be subtracted from the uninitialized range so that the new range is relative to the mapped range and avoid (very scary) out of bounds writes.
Testing
None.