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    <p>I'm assuming the above code is calling the C functions <code>malloc()</code> and <code>free()</code>...</p> <p>If 1st <code>malloc()</code> fails, you arrive at <code>dealloc_1</code> with whatever garbage is in <code>r11</code> and <code>r12</code> after returning from the <code>malloc()</code>.</p> <p>If 2nd <code>malloc()</code> fails, you arrive at <code>dealloc_1</code> with whatever garbage is in <code>r12</code> after returning from the <code>malloc()</code>.</p> <p>Therefore, you have to zero out <code>r11</code> and <code>r12</code> before doing the first allocation.</p> <p>Since this is 64-bit mode, all pointers/addresses and sizes are normally 64-bit. When you pass one of those to a function, it has to be 64-bit. So, <code>push dword 16</code> isn't quite right. It should be <code>push qword 16</code> instead. Likewise, when you are removing these parameters from the stack, you have to remove exactly as many bytes as you've put there, so <code>add rsp, 4</code> must change to <code>add rsp, 8</code>.</p> <p>Finally, I don't know which registers <code>malloc()</code> and <code>free()</code> preserve and which they don't. You may need to save and restore the so-called <code>volatile registers</code> (see your C compiler documentation). The same holds for the code not shown. It must preserve <code>r11</code> and <code>r12</code> so they can be used for deallocation. <strong>EDIT</strong>: And I'd check if it's the right way of passing parameters through the stack (again, see your compiler documentation).</p> <p><strong>EDIT</strong>: you're testing <code>r11</code> for 0 right before 2nd <code>free()</code>. It should be <code>r12</code>. But <code>free()</code> doesn't really mind receiving NULL pointers. So, these checks can be removed.</p> <p>Pay attention to your code.</p>
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