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codeql/cpp/ql/src/Critical/NewFreeMismatch.qhelp
2018-08-02 17:53:23 +01:00

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<!DOCTYPE qhelp PUBLIC
"-//Semmle//qhelp//EN"
"qhelp.dtd">
<qhelp>
<overview>
<p>
This rule finds <code>delete</code> expressions whose argument is a pointer that points to memory
allocated using the <code>malloc</code> function, and calls to <code>free</code> whose argument is a
pointer that points to memory allocated using the <code>new</code> operator. Behavior in such cases
is undefined and should be avoided.
</p>
</overview>
<recommendation>
<p>
Use the <code>delete</code> operator when freeing memory allocated with <code>new</code>, and the
<code>free</code> function when freeing memory allocated with <code>malloc</code>.
</p>
</recommendation>
<example><sample src="NewFreeMismatch.cpp" />
</example>
<references>
<li>isocpp.org 'Standard C++', "<a href="https://isocpp.org/wiki/faq/freestore-mgmt#mixing-malloc-and-delete">Can I free() pointers allocated with new? Can I delete pointers allocated with malloc()?</a>"</li>
<li>Wikipedia, "<a href="https://en.wikipedia.org/wiki/New_and_delete_(C%2B%2B)#Relation_to_malloc_and_free">Relation to malloc and free</a>" in <i>new and delete (C++)</i>.</li>
</references>
</qhelp>