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<base href="https://bugs.llvm.org/">
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<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - LLD sometimes nondeterministically swaps _end and _edata in the string table"
href="https://bugs.llvm.org/show_bug.cgi?id=45746">45746</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>LLD sometimes nondeterministically swaps _end and _edata in the string table
</td>
</tr>
<tr>
<th>Product</th>
<td>lld
</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>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>ELF
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>thomasanderson@google.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org, smithp352@googlemail.com
</td>
</tr></table>
<p>
<div>
<pre>Issue description on Chromium bug tracker:
<a href="https://bugs.chromium.org/p/chromium/issues/detail?id=1076277#c6">https://bugs.chromium.org/p/chromium/issues/detail?id=1076277#c6</a>
Repro steps:
1. In a Linux Chromium checkout, generate build files with the following gn
args:
is_component_build = true
is_debug = true
symbol_level = 1
2. Build libevents_base.so
3. Move libevents_base.so to libevents_base.so.bak
4. Apply patch:
<a href="https://chromium-review.googlesource.com/c/chromium/src/+/2164245">https://chromium-review.googlesource.com/c/chromium/src/+/2164245</a>
5. Build libevents_base.so again
6. Diff libevents_base.so and libevents_base.so.bak:
0x820 : b51a000010001700101502000000000000000000000000005500000012000b00
'........................U.......'
bc1a000010001700101502000000000000000000000000005500000012000b00
'........................U.......'
^
0xbc0 : 9701000000000000ba1a00001000160090fe0100000000000000000000000000
'................................'
9701000000000000b51a00001000160090fe0100000000000000000000000000
'................................'
^
0x31e0 : 005f656e64005f6564617461005f5f6273735f7374617274006c69626d2e736f
'._end._edata.__bss_start.libm.so'
005f6564617461005f656e64005f5f6273735f7374617274006c69626d2e736f
'._edata._end.__bss_start.libm.so'
++++++++++
+++++
0x2e9e0 : 287c000012000000000000000000000000000000000000002f7c000010001700
'(|....................../|......'
287c000012000000000000000000000000000000000000002f7c000010001600
'(|....................../|......'
^
0x2ea00 : 10150200000000000000000000000000347c00001000160090fe010000000000
'................4|..............'
90fe0100000000000000000000000000367c0000100017001015020000000000
'................6|..............'
^^^^ ^ ^ ^ +++
^
0x367a0 : 6e7600737472636d70005f656e64005f6564617461005f5f6273735f73746172
'nv.strcmp._end._edata.__bss_star'
6e7600737472636d70005f6564617461005f656e64005f5f6273735f73746172
'nv.strcmp._edata._end.__bss_star'
^ ++ ++ ++
+++++
It looks like the only change is _edata and _end have swapped places in the
string table (and the pointers to them have therefore swapped as well). All of
the libraries on the link line are the same except for libkeycodes_x11.so, but
this library has the same SONAME and symbol table before/after the patch so it
should not affect libevents_base.so.</pre>
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