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<base href="https://bugs.llvm.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - No sanity checking of array size with width specifier ?"
href="https://bugs.llvm.org/show_bug.cgi?id=36380">36380</a>
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<th>Summary</th>
<td>No sanity checking of array size with width specifier ?
</td>
</tr>
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<th>Product</th>
<td>new-bugs
</td>
</tr>
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<th>Version</th>
<td>5.0
</td>
</tr>
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<th>Hardware</th>
<td>PC
</td>
</tr>
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<th>OS</th>
<td>Linux
</td>
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<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>enhancement
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>new bugs
</td>
</tr>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>dcb314@hotmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>Given the following code:
# include <stdio.h>
extern void g( FILE * fp);
void f( FILE * fp)
{
char buf[ 10];
while (fscanf( fp, "%10s", buf))
;
while (fscanf( fp, "%5s", buf))
;
while (fscanf( fp, "%20s", buf))
;
g( fp);
}
then clang doesn't seem to sanity check the size in the % specifier
against the buffer size. Please note that %10s isn't the correct size.
That's a well known off by one error.
Here is static analyser cppcheck doing something suitable:
[sep9a.cc:13]: (error) Width 10 given in format string (no. 1) is larger than
destination buffer 'buf[10]', use %9s to prevent overflowing it.
[sep9a.cc:17]: (error) Width 20 given in format string (no. 1) is larger than
destination buffer 'buf[10]', use %9s to prevent overflowing it.</pre>
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</p>
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