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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Spurious use after free warning"
href="https://llvm.org/bugs/show_bug.cgi?id=26221">26221</a>
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<th>Summary</th>
<td>Spurious use after free warning
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
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<th>Version</th>
<td>3.8
</td>
</tr>
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<th>Hardware</th>
<td>PC
</td>
</tr>
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<th>OS</th>
<td>All
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>Static Analyzer
</td>
</tr>
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<th>Assignee</th>
<td>kremenek@apple.com
</td>
</tr>
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<th>Reporter</th>
<td>sitsofe@yahoo.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
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<div>
<pre>Created <span class=""><a href="attachment.cgi?id=15677" name="attach_15677" title="C program that demonstrates spurious use after free warning">attachment 15677</a> <a href="attachment.cgi?id=15677&action=edit" title="C program that demonstrates spurious use after free warning">[details]</a></span>
C program that demonstrates spurious use after free warning
Description of the problem:
Code that copies data being pointed at into a new variable which goes on to
then free the original pointer triggers a spurious use after free error.
Steps to reproduce:
1. Compile the attached C program using
scan-build-3.8 cc -O1 spurious-use-after-free.c -c
Expected results:
No warnings.
Actual results:
# scan-build-3.8 cc -O1 spurious-use-after-free.c -c
scan-build: Using '/usr/lib/llvm-3.8/bin/clang' for static analysis
spurious-use-after-free.c:15:5: warning: Use of memory after it is freed
return item->next; // Flagged as use after free
^~~~~~~~~~~~~~~~~
1 warning generated.
scan-build: 1 bug found.
scan-build: Run 'scan-view /tmp/scan-build-2016-01-20-133203-7599-1' to examine
bug reports.
Additional information:
This problem was identified and the reduced test case was produced by Barry
Davis of StorMagic.
Version information:
LLVM packages installed from <a href="http://llvm.org/apt/wily/">http://llvm.org/apt/wily/</a>
Ubuntu clang version 3.8.0-svn257294-1~exp1 (trunk) (based on LLVM 3.8.0)
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin</pre>
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