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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - alpha.unix.cstring.OutOfBounds wrongly triggers for flexible array members"
href="https://bugs.llvm.org/show_bug.cgi?id=48136">48136</a>
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<th>Summary</th>
<td>alpha.unix.cstring.OutOfBounds wrongly triggers for flexible array members
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<th>Product</th>
<td>clang
</td>
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<th>Version</th>
<td>trunk
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>All
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<th>Status</th>
<td>NEW
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>Static Analyzer
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<th>Assignee</th>
<td>dcoughlin@apple.com
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<th>Reporter</th>
<td>tss@iki.fi
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<th>CC</th>
<td>dcoughlin@apple.com, llvm-bugs@lists.llvm.org
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<pre>We've been using alpha.unix checks, but OutOfBounds is annoyingly triggering
with flexible array members. Apparently it thinks they are 0 sized.
Using clang 12 from git, checked out Oct 27 2020.
# scan-build -enable-checker alpha.unix gcc test.c -o test
test.c:13:2: warning: Memory set function overflows the destination buffer
[alpha.unix.cstring.OutOfBounds]
memset(str->data, 'x', 10);
^~~~~~~~~~~~~~~~~~~~~~~~~~
When test.c contains:
#include <stdlib.h>
#include <string.h>
struct str {
size_t len;
char data[];
};
int main(void)
{
struct str *str = malloc(sizeof(str) + 10);
str->len = 10;
memset(str->data, 'x', 10);
return 0;
}</pre>
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