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Fix an OOB read in the demangler #31793

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Merged
merged 1 commit into from
May 15, 2020
Merged

Fix an OOB read in the demangler #31793

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3 changes: 1 addition & 2 deletions include/swift/Demangling/Demangler.h
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Original file line number Diff line number Diff line change
Expand Up @@ -565,8 +565,7 @@ class Demangler : public NodeFactory {
NodePointer demangleValueWitness();

NodePointer demangleTypeMangling();
NodePointer demangleSymbolicReference(unsigned char rawKind,
const void *at);
NodePointer demangleSymbolicReference(unsigned char rawKind);

bool demangleBoundGenerics(Vector<NodePointer> &TypeListList,
NodePointer &RetroactiveConformances);
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10 changes: 6 additions & 4 deletions lib/Demangling/Demangler.cpp
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Expand Up @@ -677,12 +677,14 @@ NodePointer Demangler::demangleTypeMangling() {
return TypeMangling;
}

NodePointer Demangler::demangleSymbolicReference(unsigned char rawKind,
const void *at) {
NodePointer Demangler::demangleSymbolicReference(unsigned char rawKind) {
// The symbolic reference is a 4-byte machine integer encoded in the following
// four bytes.
if (Pos + 4 > Text.size())
return nullptr;
const void *at = Text.data() + Pos;
int32_t value;
memcpy(&value, Text.data() + Pos, 4);
memcpy(&value, at, 4);
Pos += 4;

// Map the encoded kind to a specific kind and directness.
Expand Down Expand Up @@ -734,7 +736,7 @@ NodePointer Demangler::demangleOperator() {
goto recur;
case 1: case 2: case 3: case 4: case 5: case 6: case 7: case 8:
case 9: case 0xA: case 0xB: case 0xC:
return demangleSymbolicReference((unsigned char)c, Text.data() + Pos);
return demangleSymbolicReference((unsigned char)c);
case 'A': return demangleMultiSubstitutions();
case 'B': return demangleBuiltinType();
case 'C': return demangleAnyGenericType(Node::Kind::Class);
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