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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Hi,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">FlowDroid uses its own alias analysis, because the one integrated in Soot has limitations. First and foremost, Soot’s PtS-based analysis only handles base objects
and single field dereferences. FlowDroid, on the other hand, uses access paths, which model sequences of field dereferences with an arbitrary length. Secondly, we need a context-sensitive alias analysis, which Soot does not provide. You can read up on the
details in my PhD thesis [1], which contains a complete section on aliasing.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">The backwards analysis stops when it reaches an allocation site for the base value for the access path which it is currently propagating. In other words, when
going back, we check whether the current variable (base of the access path) is overwritten. If so, no aliases can be created before.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Best regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"> Steven<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">[1] http://tuprints.ulb.tu-darmstadt.de/5937/<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> Soot-list [mailto:soot-list-bounces@cs.mcgill.ca]
<b>On Behalf Of </b>Sri Shaila G<br>
<b>Sent:</b> Thursday, January 18, 2018 1:20 AM<br>
<b>To:</b> soot-list@cs.mcgill.ca<br>
<b>Subject:</b> [Soot-list] Doubt in flowdroid alias analysis<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Hi,<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">I have a doubt in flowdroid. My doubts are as follows.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">1.I understand that you are using the backwards analysis in flowdroid to find out the aliases of the tainted variables. Why did you choose the backwards analysis method to find the aliases instead of using the pointsToAnalysis in Soot.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">2. When does the backwards analysis stop?<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Thank you<o:p></o:p></p>
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