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<base href="https://llvm.org/bugs/" />
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Crash in LLParser with undefined tbaa metadata"
href="https://llvm.org/bugs/show_bug.cgi?id=27196">27196</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Crash in LLParser with undefined tbaa metadata
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</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>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>LLVM assembly language parser
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>philip.pfaffe@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
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<div>
<pre>Created <span class=""><a href="attachment.cgi?id=16165" name="attach_16165" title="Crashing Testcase">attachment 16165</a> <a href="attachment.cgi?id=16165&action=edit" title="Crashing Testcase">[details]</a></span>
Crashing Testcase
If IR is annotated with TBAA metadata but the referenced MD isn't declared, an
assertion in MDNode::getOperand is triggered. In LLParser::ValidateEndOfModule
in the call to UpgradeInstWithTBAATag, there is an unconditional check
"isa<MDNode>(MD->getOperand(0))", which ends badly if MD->getNumOperands() is
0.
Crashing testcase attached.
A similar unchecked call chain occurs in BitcodeReader, but i haven't been able
to reproduce the error there, and i'm not sure whether the bitcode format
actually allows for this problem to arise.
A possible fix for the LLParser could be this:
--- a/lib/AsmParser/LLParser.cpp
+++ b/lib/AsmParser/LLParser.cpp
@@ -100,8 +100,9 @@ void LLParser::restoreParsingState(const SlotMapping
*Slots) {
/// ValidateEndOfModule - Do final validity and sanity checks at the end of
the
/// module.
bool LLParser::ValidateEndOfModule() {
- for (unsigned I = 0, E = InstsWithTBAATag.size(); I < E; I++)
- UpgradeInstWithTBAATag(InstsWithTBAATag[I]);
+ for (auto *I : InstsWithTBAATag)
+ if (I->getMetadata(LLVMContext::MD_tbaa)->getNumOperands() > 0)
+ UpgradeInstWithTBAATag(I);
// Handle any function attribute group forward references.
for (std::map<Value*, std::vector<unsigned> >::iterator</pre>
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