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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 --- - gold+gold-plugin may unmap file before done"
href="http://llvm.org/bugs/show_bug.cgi?id=22482">22482</a>
</td>
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<tr>
<th>Summary</th>
<td>gold+gold-plugin may unmap file before done
</td>
</tr>
<tr>
<th>Product</th>
<td>tools
</td>
</tr>
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<th>Version</th>
<td>trunk
</td>
</tr>
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<th>Hardware</th>
<td>PC
</td>
</tr>
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<th>OS</th>
<td>All
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>normal
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>gold-plugin
</td>
</tr>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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</tr>
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<th>Reporter</th>
<td>jvoung@google.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
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</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>I've run into a situation where a 32-bit linux LLVM + gold-plugin + binutils
will unmap a file view in getModuleForFile(), and then try to access the file
view buffer after that.
Timeline is roughly:
=====
getModuleForFile(...) {
ld_plugin_input_file File;
if (get_input_file(F.handle, &File) != LDPS_OK)
// ...
const void *View;
if (get_view(F.handle, &View) != LDPS_OK)
// ...
// ... View is fine. It points to the mmap'ed version of the file contents.
// Set up Buffer/BufferRef based on the View
if (release_input_file(F.handle) != LDPS_OK)
// ... View is no longer fine. release_input_file **may** end up unmapping.
// Attempt to access the buffers more, and crash.
// ...
}
====
I've only been able to reproduce this where binutils and llvm are built as
32-bit executables. Things work fine as 64-bit executables, and the
release_input_file() does not unmap the view.
For 64-bit gold's File_read::clear_views() hits this case:
else if ((p->second->should_cache()
|| p->second == this->whole_file_view_)
&& keep_files_mapped)
should_delete = false;
and then does not delete the view, while on 32-bit it does.
I'm not sure exactly why yet, but I'm wondering if the gold-plugin's call to
release_input_file() should be later.</pre>
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</p>
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