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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Suspicious use of sizeof(pointer) in FuzzerMutate.cpp"
href="https://bugs.llvm.org/show_bug.cgi?id=36148">36148</a>
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<th>Summary</th>
<td>Suspicious use of sizeof(pointer) in FuzzerMutate.cpp
</td>
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<th>Product</th>
<td>new-bugs
</td>
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<th>Version</th>
<td>5.0
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Linux
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>new bugs
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>wolf@behrenhoff.de
</td>
</tr>
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
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<p>
<div>
<pre>In file lib/Fuzzer/FuzzerMutate.cpp, the function RandCh (lines 63--67) looks
like this:
static char RandCh(Random &Rand) {
if (Rand.RandBool()) return Rand(256);
const char *Special = "!*'();:@&=+$,/?%#[]012Az-`~.\xff\x00";
return Special[Rand(sizeof(Special) - 1)];
}
Special is thus a pointer to char. In the return line sizeof(pointer)-1 is used
as index. I think the intention was to return any of the predefined characters,
not any of the first 4-1=3 or 8-1=7 characters (or whatever size a pointer is
on the target platform).
I suggest using an array instead of a pointer:
const char Special[] = "!*'();:@&=+$,/?%#[]012Az-`~.\xff\x00";
I haven't tested this, but surely the sizeof(pointer) is wrong :-)
This bug is at least present in the 5.0.1 download. If it is also in 6 or
trunk: I don't know. Please check!
Cheers!</pre>
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</p>
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