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<base href="https://bugs.llvm.org/">
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<body><table border="1" cellspacing="0" cellpadding="8">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - msan: incorrect origin for stack variables"
href="https://bugs.llvm.org/show_bug.cgi?id=37206">37206</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>msan: incorrect origin for stack variables
</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>
<tr>
<th>OS</th>
<td>Linux
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>enhancement
</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>dvyukov@google.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>#include <stdio.h>
int main()
{
volatile char a, b, c, d, e, f, g, h;
volatile char x, y;
c = x;
d = y;
if (c)
printf("here\n");
return 0;
}
$ clang -v
clang version 7.0.0 (trunk 326052)
$ clang test.c -fsanitize=memory -fsanitize-memory-track-origins -g
$ ./a.out
==259013==WARNING: MemorySanitizer: use-of-uninitialized-value
#0 0x49a1a6 in main test.c:9:6
#1 0x7f8dd562a2b0 in __libc_start_main
(/lib/x86_64-linux-gnu/libc.so.6+0x202b0)
#2 0x41d5f9 in _start (a.out+0x41d5f9)
Uninitialized value was stored to memory at
#0 0x49a116 in main test.c:8:4
#1 0x7f8dd562a2b0 in __libc_start_main
(/lib/x86_64-linux-gnu/libc.so.6+0x202b0)
Uninitialized value was created by an allocation of 'y' in the stack frame of
function 'main'
#0 0x499b10 in main test.c:4
SUMMARY: MemorySanitizer: use-of-uninitialized-value test.c:9:6 in main
Uninit values is created by variable 'x', not 'y'.
MSAN should align local variables to origin granularity.</pre>
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