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<base href="https://llvm.org/bugs/" />
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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 --- - llvm-mc crashes with invalid output-asm-variant"
href="https://llvm.org/bugs/show_bug.cgi?id=28488">28488</a>
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</tr>
<tr>
<th>Summary</th>
<td>llvm-mc crashes with invalid output-asm-variant
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
<tr>
<th>Version</th>
<td>3.8
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux
</td>
</tr>
<tr>
<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>MC
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>jvoss+bugs@altsci.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Giving an invalid value to output-asm-variant causes llvm-mc to crash
dereferencing a null pointer.
echo '0xb0 0x0b' | llvm-mc --disassemble -triple=x86_64 --output-asm-variant=2
#0 0x00007ff528254708 llvm::sys::PrintStackTrace(llvm::raw_ostream&)
(/usr/bin/../lib64/libLLVMSupport.so.3.8+0xcd708)
#1 0x00007ff5282526f6 llvm::sys::RunSignalHandlers()
(/usr/bin/../lib64/libLLVMSupport.so.3.8+0xcb6f6)
#2 0x00007ff5282529cb (/usr/bin/../lib64/libLLVMSupport.so.3.8+0xcb9cb)
#3 0x00007ff5278f9160 (/lib64/libc.so.6+0x33160)
#4 0x000000000040987d _init (/usr/bin/llvm-mc+0x40987d)
#5 0x00007ff5278e6790 __libc_start_main (/lib64/libc.so.6+0x20790)
#6 0x000000000040a429 _init (/usr/bin/llvm-mc+0x40a429)
Stack dump:
0. Program arguments: llvm-mc --disassemble -triple=x86_64
--output-asm-variant=2
Segmentation fault
gdb llvm-mc
(gdb) run --disassemble -triple=x86_64 --output-asm-variant=2
0xb0 0x0b
Program received signal SIGSEGV, Segmentation fault.
0x000000000040987d in main ()
(gdb) bt
#0 0x000000000040987d in main ()
(gdb) disassemble
...
=> 0x000000000040987d <+7005>: mov %al,0x29(%rdx)
(gdb) i r
...
rdx 0x0 0</pre>
</div>
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