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<p>in the page cache, but not written to, might result in a <a href="page.php?w=zero-byte_file">zero-byte file</a> at a later read.</p>

<p>However, not all cached pages can be written to as program code is often mapped as <a href="page.php?w=file_system_permissions">read-only</a> or <a href="page.php?w=copy-on-write">copy-on-write</a>; in the latter case, modifications to code will only be visible to the process itself and will not be written to disk.</p>

<p><big> Side-channel attacks </big></p>
<p>In 2019, security researchers demonstrated <a href="page.php?w=side-channel_attack">side-channel attack</a>s</p><p>
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