<html>
<head>
<base href="https://bugs.llvm.org/">
</head>
<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - [coroutines] optimized code references subobject of promise as temporary"
href="https://bugs.llvm.org/show_bug.cgi?id=47085">47085</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>[coroutines] optimized code references subobject of promise as temporary
</td>
</tr>
<tr>
<th>Product</th>
<td>new-bugs
</td>
</tr>
<tr>
<th>Version</th>
<td>10.0
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>enhancement
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>new bugs
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>me@xecycle.info
</td>
</tr>
<tr>
<th>CC</th>
<td>htmldeveloper@gmail.com, llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=23834" name="attach_23834" title="reproducing source code">attachment 23834</a> <a href="attachment.cgi?id=23834&action=edit" title="reproducing source code">[details]</a></span>
reproducing source code
Using 10.0.1 as packaged by Arch Linux, attached code when compiled with
"-std=gnu++17 -fcoroutines-ts -O2 -stdlib=libc++" triggers use-after-free
reports in valgrind, but runs ok at -O0. It has
__attribute__((noinline))
void f(std::string s, coroutine_handle<> h)
{
puts(s.c_str());
h.destroy();
}
and
void await_suspend(coroutine_handle<> h)
{
f(std::move(pr->retval), h);
}
Here, calling f() needs a temporary std::string, copied from member of
coroutine promise; at -O0 it is created by alloca, but at -O2 it points to the
original object, and destroyed after returned from f(). Because f() freed the
coroutine, ~std::string() caused a use-after-free.</pre>
</div>
</p>
<hr>
<span>You are receiving this mail because:</span>
<ul>
<li>You are on the CC list for the bug.</li>
</ul>
</body>
</html>