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GP-4514 Add check preventing multiple unlabeled switch targets

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caheckman 2024-04-11 23:15:10 +00:00
parent 20f5bd9bec
commit 3c3591f6dc
6 changed files with 127 additions and 59 deletions
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55
Ghidra/Features/Decompiler/src/decompile/cpp/block.cc
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@ -2613,30 +2613,47 @@ void BlockBasic::printRaw(ostream &s) const
}
}
/// \brief Check if there is meaningful activity between two branch instructions
/// \brief Check for values created in \b this block that flow outside the block.
///
/// The first branch is assumed to be a CBRANCH one edge of which flows into
/// the other branch. The flow can be through 1 or 2 blocks. If either block
/// performs an operation other than MULTIEQUAL, INDIRECT (or the branch), then
/// return \b false.
/// \param first is the CBRANCH operation
/// \param path is the index of the edge to follow to the other branch
/// \param last is the other branch operation
/// \return \b true if there is no meaningful activity
bool BlockBasic::noInterveningStatement(PcodeOp *first,int4 path,PcodeOp *last)
/// The block can calculate a value for a BRANCHIND or CBRANCH and can copy values and this method will still
/// return \b true. But calculating any value used outside the block, writing to an addressable location,
/// or performing a CALL or STORE causes the method to return \b false.
/// \return \b true if no value is created that can be used outside of the block
bool BlockBasic::noInterveningStatement(void) const
{
BlockBasic *curbl = (BlockBasic *)first->getParent()->getOut(path);
for(int4 i=0;i<2;++i) {
if (!curbl->hasOnlyMarkers()) return false;
if (curbl != last->getParent()) {
if (curbl->sizeOut() != 1) return false; // Intervening conditional branch
list<PcodeOp *>::const_iterator iter;
const PcodeOp *bop;
OpCode opc;
for(iter=op.begin();iter!=op.end();++iter) {
bop = *iter;
if (bop->isMarker()) continue;
if (bop->isBranch()) continue;
if (bop->getEvalType() == PcodeOp::special) {
if (bop->isCall())
return false;
opc = bop->code();
if (opc == CPUI_STORE || opc == CPUI_NEW)
return false;
}
else {
opc = bop->code();
if (opc == CPUI_COPY || opc == CPUI_SUBPIECE)
continue;
}
const Varnode *outvn = bop->getOut();
if (outvn->isAddrTied())
return false;
list<PcodeOp *>::const_iterator iter = outvn->beginDescend();
while(iter!=outvn->endDescend()) {
PcodeOp *op = *iter;
if (op->getParent() != this)
return false;
++iter;
}
else
return true;
curbl = (BlockBasic *)curbl->getOut(0);
}
return false;
return true;
}
/// If there exists a CPUI_MULTIEQUAL PcodeOp in \b this basic block that takes the given exact list of Varnodes