<!DOCTYPE qhelp PUBLIC

"-//Semmle//qhelp//EN"

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<qhelp>

<overview>

<p>

This query finds pointer dereferences that use a pointer returned from a function which may return NULL. Always

check your pointers for NULL-ness before dereferencing them. Dereferencing a null pointer and attempting to

modify its contents can lead to anything from a segmentation fault to corruption of important system data

(for example, the interrupt table in some architectures).

</p>

</overview>

<recommendation>

<p>

Add a null check before dereferencing the pointer, or modify the function so that it always returns a non-null value.

</p>

</recommendation>

<example>

<p>In this example, the function is not protected from dereferencing a null pointer. It should be updated to ensure that

this cannot happen.

</p>

<sample src="MissingNullTest.cpp" />

</example>

<references>

<li>SEI CERT C Coding Standard: <a href="https://wiki.sei.cmu.edu/confluence/display/c/EXP34-C.+Do+not+dereference+null+pointers">EXP34-C. Do not dereference null pointers</a>.</li>

</references>

</qhelp>