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<base href="http://llvm.org/bugs/" />
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - MemorySanitizer false positive in module destructors"
href="http://llvm.org/bugs/show_bug.cgi?id=17377">17377</a>
</td>
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<th>Summary</th>
<td>MemorySanitizer false positive in module destructors
</td>
</tr>
<tr>
<th>Product</th>
<td>compiler-rt
</td>
</tr>
<tr>
<th>Version</th>
<td>unspecified
</td>
</tr>
<tr>
<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>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>compiler-rt
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>eugeni.stepanov@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>$ cat 1.cc
#include <stdio.h>
#include <stdlib.h>
class A {
public:
~A() {
if (this)
exit(1);
}
};
A a;
__attribute__((noinline))
void f(long x) {
}
int main(void) {
long x;
long * volatile p = &x;
f(*p);
return 0;
}
$ ./build/bin/clang++ -fsanitize=memory 1.cc -o 1 -O0 -g
$ MSAN_SYMBOLIZER_PATH=build/bin/llvm-symbolizer ./1
==19875== WARNING: MemorySanitizer: use-of-uninitialized-value
#0 0x7f5818982037 in A::~A() /code/llvm/1.cc:6
#1 0x7f5818981fbd in A::~A() /code/llvm/1.cc:5
#2 0x7f581754b900 in __run_exit_handlers
/build/buildd/eglibc-2.15/stdlib/exit.c:78
#3 0x7f581754b984 in __GI_exit /build/buildd/eglibc-2.15/stdlib/exit.c:100
#4 0x7f5817531773 in __libc_start_main
/build/buildd/eglibc-2.15/csu/libc-start.c:258
#5 0x7f5818981cf0 in _start (/code/llvm/1+0x52cf0)
The cause is obvious: module destructors get stale argument shadow due to being
called from (uninstrumented) libc.</pre>
</div>
</p>
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