<p>This is using opensips 2.1 at commit <a href="https://github.com/OpenSIPS/opensips/commit/ee99ac71d8718c93c29e28e6a5266287491f17a5" class="commit-link"><tt>ee99ac7</tt></a> in a production environment. OpenSIPS is configured to generate coredump, <a href="https://github.com/OpenSIPS/opensips/files/56763/core.txt">core.txt</a> has <code>bt full</code> + <code>print</code> of variables in last 3 stack entries.</p>
<p>The issue in the code is relatively simple to understand,</p>
<pre><code>pf = n->prev;
</code></pre>
<p>is followed by</p>
<pre><code>*pf = n->u.nxt_free;
</code></pre>
<p>(lines 167 and 171 of mem/f_malloc.c) without checking whether <code>n->prev</code> actually exists. However this is fairly old code so there must be some assumptions that made the test unnecessary at the time — but maybe not anymore, or maybe there's some environment dependency I need to check.</p>
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