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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - xcb_send_event() reads beyond end of argument / is hard to use correctly"
href="https://bugs.freedesktop.org/show_bug.cgi?id=99946">99946</a>
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<th>Summary</th>
<td>xcb_send_event() reads beyond end of argument / is hard to use correctly
</td>
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<th>Product</th>
<td>XCB
</td>
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<th>Version</th>
<td>unspecified
</td>
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<th>Hardware</th>
<td>Other
</td>
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<th>OS</th>
<td>All
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>medium
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<th>Component</th>
<td>Library
</td>
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<th>Assignee</th>
<td>xcb@lists.freedesktop.org
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<th>Reporter</th>
<td>psychon@znc.in
</td>
</tr>
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<th>QA Contact</th>
<td>xcb@lists.freedesktop.org
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<pre><a href="https://bugreports.qt.io/browse/QTBUG-56518">https://bugreports.qt.io/browse/QTBUG-56518</a> is about valgrind warnings that
occur in Qt. The code in question does basically:
xcb_unmap_notify_event_t event;
set all fields of event;
xcb_send_event(c, false, root, mask, &event);
The problem here is that sizeof(event) is 16 while xcb_send_event() expects 32
bytes of event data. So the argument needs to be "something bigger". This is
quite unintuitive and it seems like everyone using xcb_send_event() is getting
this wrong. (I would claim that I know may way around XCB and I did not know
this!)
Can there be a version of xcb_send_event() which gets a length argument? Are
there any other ideas on how this could be made safer or more obvious?</pre>
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