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Code Issues Releases Wiki Activity

Prevent Symbol storage conflicts

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This commit is contained in:
caheckman 2020-07-10 14:26:33 -04:00
parent 4f63568bdb
commit 2ea73a65a0
2 changed files with 42 additions and 2 deletions
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1
Ghidra/Features/Decompiler/src/decompile/cpp/funcdata.hh
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@ -87,6 +87,7 @@ class Funcdata {
// Low level Varnode functions
void setVarnodeProperties(Varnode *vn) const; ///< Look-up boolean properties and data-type information
HighVariable *assignHigh(Varnode *vn); ///< Assign a new HighVariable to a Varnode
Symbol *handleSymbolConflict(SymbolEntry *entry,Varnode *vn); ///< Handle two variables with matching storage
bool syncVarnodesWithSymbol(VarnodeLocSet::const_iterator &iter,uint4 flags,Datatype *ct);
bool descend2Undef(Varnode *vn); ///< Transform all reads of the given Varnode to a special \b undefined constant

43
Ghidra/Features/Decompiler/src/decompile/cpp/funcdata_varnode.cc
View file

@ -866,6 +866,46 @@ bool Funcdata::syncVarnodesWithSymbols(const ScopeLocal *lm,bool typesyes)
return updateoccurred;
}
/// A Varnode overlaps the given SymbolEntry. Make sure the Varnode is part of the variable
/// underlying the Symbol. If not, remap things so that the Varnode maps to a distinct Symbol.
/// In either case, attach the appropriate Symbol to the Varnode
/// \param entry is the given SymbolEntry
/// \param vn is the overlapping Varnode
/// \return the Symbol attached to the Varnode
Symbol *Funcdata::handleSymbolConflict(SymbolEntry *entry,Varnode *vn)
{
if (vn->isInput() || vn->isAddrTied() ||
vn->isPersist() || vn->isConstant() || entry->isDynamic()) {
vn->setSymbolEntry(entry);
return entry->getSymbol();
}
HighVariable *high = vn->getHigh();
Varnode *otherVn;
HighVariable *otherHigh = (HighVariable *)0;
// Look for a conflicting HighVariable
VarnodeLocSet::const_iterator iter = beginLoc(entry->getSize(),entry->getAddr());
while(iter != endLoc()) {
otherVn = *iter;
if (otherVn->getSize() != entry->getSize()) break;
if (otherVn->getAddr() != entry->getAddr()) break;
HighVariable *tmpHigh = otherVn->getHigh();
if (tmpHigh != high) {
otherHigh = tmpHigh;
break;
}
++iter;
}
if (otherHigh == (HighVariable *)0) {
vn->setSymbolEntry(entry);
return entry->getSymbol();
}
// If we reach here, we have a conflicting variable
buildDynamicSymbol(vn);
return vn->getSymbolEntry()->getSymbol();
}
/// \brief Update properties (and the data-type) for a set of Varnodes associated with one Symbol
///
/// The set of Varnodes with the same size and address all have their boolean properties
@ -994,8 +1034,7 @@ Symbol *Funcdata::linkSymbol(Varnode *vn)
// Find any entry overlapping base address
entry = localmap->queryProperties(vn->getAddr(), 1, usepoint, flags);
if (entry != (SymbolEntry *) 0) {
sym = entry->getSymbol();
vn->setSymbolEntry(entry);
sym = handleSymbolConflict(entry, vn);
}
else { // Must create a symbol entry
if (!vn->isPersist()) { // Only create local symbol